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tionable whether they will play more than moderate-sized stations dotted over the a minor part as compared with the steam- area, results in a small decrease in the cost ship, railway and motor transport. of production of the electricity, because in

Electricity.The supply and use of the super-stations larger and slightly more electricity has developed rapidly in recent economical engines are employed, while the years. For lighting it is the rival of gas, larger stations permit of higher organizathough each has its advantages. As a tion and more elaborate labor-saving apmeans of transmitting power over long pliances. Further, if in the future the distances it has no rival, and its efficiency recovery of the by-products of coal should is so high that, when generated on a large become a practical realization as part of scale and distributed over large areas, it the process in the manufacture of the is a cheap and trustworthy source of power electric current, the larger super-stations for working factories, tramways, suburban present greater facilities than the smaller railways and innumerable other purposes, stations. On the other, super-stations inincluding metallurgical and chemical proc- volve the transmission of the electricity esses. It is rapidly superseding locally over greater distances, and consequently generated steam-power, and is a rival to greater capital expenditure and cost of the small- and moderate-sized gas and oil maintenance of mains and transmission engines. It has made practicable the use apparatus, and greater electrical transof water-power through the generation of mission losses, while the larger generating electricity in bulk at the natural falls, unit takes longer to overhaul or repair, from which the power is transmitted to the and consequently a larger percentage of consumers, sometimes at great distances. spare plant is necessary.

Fifteen years ago electricity was gen- The greatest element in reducing the erated chiefly by large reciprocating steam- cost of electricity is the provision of a engines, direct-coupled to dynamos or good load factor; in other words, the alternators, but of late years steam tur- utilization of the generating plant and bines have in most instances replaced mains to the greatest extent during the them, and are now exclusively used in twenty-four hours of each day throughout large generating stations because of their the year. This is a far more important smaller cost and greater economy in fuel. consideration than the size of the station, The size of the turbines may vary from a and it is secured to the best advantage in few thousand horse-power up to about 50,- most cases by a widespread network of 000 h.p. At the end of last year the mains, supplying a diversity of consumers central electric stations in the United and users, each requiring current at differKingdom contained plant aggregating ent times of the day. The total load of 2,750,000 kilowatts, 79 per cent. of which each station being thus an average of the was driven by steam turbines.

individual loads of a number of consumers Much discussion has taken place as to is, in general, far less fluctuating than in the most economical size of generating the case of small generating and distribstations, their number, the size of the gen- uting systems, which supply principally erating units, and the size of the area to be one class of consumer-a state of affairs supplied. On the one hand, a compara- that exists in London, for instance, at the tively small number of very large or super- present time. It is true that there may stations, instead of a large number of be exceptional cases, such as at Kilmarnock, where a good load factor may be PHYSIOLOGICAL ISOLATION BY LOW found in a small area, but in this case the

TEMPERATURE IN BRYOPHYLLUM consumers are chiefly mills, which require

AND OTHER PLANTS current for many hours daily.

In axiate plants a physiologically active There is no golden rule to secure cheap

growing tip inhibits more or less completely electricity. The most favorable size, local- the development of other growing tips or axes ity and number of generating stations in

of the same plant within a certain distance

which varies to some extent with the intensity each area can only be arrived at by a

of physiological or metabolic activity in the close study of the local conditions, but

inhibiting tip. This physiological correlation there is no doubt that, generally speaking,

is not specific for the growing tips of stems to secure cheap electricity a widespread

and roots, but other parts of the plant, e. g., network of mains is in most cases a very leaves, may exert the same inhibiting effect important, if not an essential, factor.

to a greater or less degree. Removal of the The electrification of tramways and sub- growing tip or other inhibiting part, or a urban railways has been an undoubted sufficient decrease in its metabolic activity success where the volume of traffic has abolishes its inhibiting action upon other justified a frequent service, and it has been parts. These facts have long been known, remarkable that where suburban lines have

much experimental work has been done upon been worked by frequent and fast elec

this problem of physiological correlation and

various hypotheses have been advanced. As trical trains there has resulted a great

regards the manner in which such an effect growth of passenger traffic. The electrifi

of one part upon another at a greater or less cation of main-line railways would no

distance may conceivably be produced, there doubt result in a saving of coal; at the are apparently three possibilities: first, the same time, the economical success would growing tip may inhibit indirectly by obtainlargely depend on the broader question as ing through its greater physiological activity to whether the volume of the traffic would the greater proportion of nutritive materials suffice to pay the working expenses and necessary for growth and development; second, provide a satisfactory return the

the growing tip or other inhibiting part may

produce substances which are transported by capital.

the fluids of the plant and which exert a Municipal and company generating stations have been nearly doubled in capacity and third, the metabolic activity of the grow

specific inhibiting effect upon other parts; during the war to meet the demand from

ing tip may produce dynamic changes which munition works, steel works, chemical are conducted through the protoplasm of the works, and for many other purposes. The plant and influence the physiological condition provision of this increased supply was an of the parts which they reach. enormous help in the production of ade

As regards the first of these possibilities it quate munitions. At the commencement

is difficult to conceive how in the bean seedof the war there were few steel electric

ling, to take a concrete case, the growing tip furnaces in the country; at the end of last

can so completely deprive the buds in the axils

of the cotyledons of nutrition that they are year 117 were at work, producing 20,000

unable to grow at all, although they are very tons of steel per month, consisting chiefly

much nearer the source of both inorganic and of high-grade ferro alloys used in muni

organic nutrition than the tip. The attempt tions.

to interpret this inhibition solely in nutritive CHARLES A. PARSONS terms has proven unsatisfactory. (To be concluded)

The second possibility, the production of


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more or less specific inhibiting substances, were undertaken because it was believed that which are transported to other parts of the this method of temporarily blocking the correplant, also presents certain difficulties and in- lative factor in its passage would prove parconsistencies. In the first place every grow- ticularly fruitful in plants and would afford ing tip must be immune to the inhibiting sub- a means of testing still further the general stances which it produces, yet these substances conception of physiological axiation which has inhibit other growing tips; second, in the been formulated by one of us on the basis of normal growth of most plants new growing many different lines of zoological and botantips of stems usually arise from previously ical evidence. existing growing tips: it is not their origin These experiments are concerned with the but their later development which is inhibited; effect of low temperature as a block to the third, the correlation exists in many simple action of the growing tip upon other parts of plants, such for example as algæ, where there the plant. The method of experimentation is, so far as we know, no mechanism for the consists in subjecting to a low temperature transportation of such substances through the some portion of the plant between the inhibitplant body; fourth, the inhibiting action is ing growing tip and the part which it innot a specific function of growing tips of hibits, while the inhibiting growing tip and stems for a leaf may inhibit a bud. In short the inhibiting part which it is desired to when we attempt to interpret the facts in isolate remain at the usual temperature. More terms of inhibiting substances inconsistencies specifically a portion, two centimeters or more and contradictions began at once to appear.

in length of the stem, petiole, runner, etc., is The third possibility, that of a dynamic surrounded by a coil of tubing through which change of some sort, transmitted through the flows a current of water, at a low, controlled protoplasm, has been suggested by various temperature. In order to avoid injury, the authors, but the problem of the mechanism diameter of the coil is made large enough so by which such a transmitted change produces that it does not touch the plant, the portion an inhibiting effect has not been adequately to be inclosed is wrapped in tinfoil, the space considered.

between it and the coil is lightly packed with Most experimental work along this line has damp absorbent cotton, and finally the coil, consisted either in removing, or stopping or together with the portion of the plant surretarding the physiological activity of the in- rounded by it, is wrapped lightly with a hibiting tip or other part, or in physical bandage of dry raw cotton. In this way a isolation of the inhibited part from its action. localized region can be maintained at any Another method of attack upon the problem desired temperature above zero with very which has been but little used consists in at- slight variation, provided the temperature of tempting to block the correlative factor some- the water flowing through the coil is kept where along its path in the intact plant. If constant. In the apparatus used in these exit is possible to accomplish this blocking with- periments the temperature variation inside the out injury to the plant and to make it tem- coil can be controlled within one degree porary, i. e., reversible, the nature of the con- Centigrade. The plants are kept in a greenditions which bring about the block and the house at a temperature ranging from 20° to behavior of the parts of the plant on the two 25° C., while the region surrounded by the sides of the block may be expected to afford

coil is kept at a much lower temperature, in at least some basis for conclusions concern- most experiments at approximately 3° C., ing the nature of the correlative factor which though in some cases temperatures as high is blocked.

as 5° or even 6° have been found effective. The experiments briefly described below The results of these experiments with low

1 McCallum, Bot. Gaz., XL., 1905, attempted to temperature are briefly as follows: It is a block the correlative action by means of localized familiar fact that in Bryophyllum new plants anesthesia and obtained results of great interest. develop from the notches of the leaves when


the leaves are separated from the parent plant above the zone of low temperature shows no and placed in water or in a saturated atmos- wilting and at most only a slight retardation phere. We have found that when a length of growth for two or three days. Moreover, of 2 to 3 centimeters of the petiole is kept at the development of all axillary buds above the a temperature 2.5° to 3° and the leaf immersed zone of low temperature is inhibited as in norin water at room temperature, the notches, or mal plants, but the inhibiting factor is blocked some of them, will develop into new plants, by the low temperature zone, although water while the leaf is still attached to the parent and nutritive substances obviously pass it. plant. The low temperature does not visibly When the low temperature coil is removed injure the petiole and after its removal the from the stem the growth of the buds in the development of the notches may again be in- axils of the cotyledons may be again inhibited, hibited or retarded. Moreover, it can be and may be again started by replacing the low shown in this way that each leaf exerts a cor- temperature. If, however, the physiological relative action upon the leaf opposite and to isolation by low temperature is maintained some extent upon other leaves near it, this long enough to permit these buds to develop action extending farther down the stem than into shoots several centimeters long, they upward. For example when the petiole of one often continue to grow more or less rapidly leaf is kept at low temperature, development after the low temperature is removed and in occurs not only in the notches of this leaf

cases may even inhibit the further but in at least some of those of the opposite growth of the chief tip. In these bean seedleaf and sometimes in some of the notches of lings the effect of the low temperature zone the next pair above and of one or two pairs is visible in the growth of the buds within below, if these leaves are immersed in water. one to two days. In general the effect upon other leaves of the In the same way other axillary buds at physiological isolation of one leaf apparently higher levels of the stem may be physiologdecreases with increasing distance from the ically isolated and induced to develop, while isolated leaf and more rapidly upward than the chief growing tip continues to grow and downward.

to inhibit all buds above the zone of low Very commonly the development of the temperature. In most plants a temperature of notches is less rapid in the leaf with the low 5° or 6° C., constitutes an effective block temperature zone on its petiole than in the to the inhibiting action of the chief growing opposite leaf, although the two leaves them- tip for several days, but these temperatures selves are at the same temperature. This are near the upper limit of effectiveness for difference in rate of development is probably this species, and adjustment or acclimation of due to the fact that the low temperature zone the cooled zone gradually occurs to such a brings about some disturbance in the move- degree that the buds which were at first physment of nutrition to the leaf and so delays iologically isolated are again inhibited and somewhat the development of its buds.

cease to grow even before the low temperature Young plants of the scarlet runner bean is removed. When lower temperatures are Phaseolus multiflorus, and Lima bean, Phase- used such acclimation may occur to some exolus macrocarpus have also been much used in tent, but is less rapid. these experiments with even more satisfactory Physiological isolation of the runner-tip of results than Bryophyllum. In these species Saxifraga sarmentosa may also be brought buds are present in the axils of the cotyledons, about by low temperature. The runners of but in normal plants these buds never develop this plant, like those of the strawberry and beyond minute outgrowths. When a length various other forms, grow to a certain length, of 2 or 3 centimeters of the stem above the and then the bud at the tip of the runner cotyledons and below the first pair of leaves is develops into a new plant, and growth in inclosed in a coil at 3o, 4o and ally even 5° length of the runner ceases. The more active C., these buds develop, although the plant the parent plant, the longer the runner grows before its tip develops. When the plants are purely physical transportation in the fluids in good condition the runners attain a length flowing through preformed channels” in the of 20 to 30 centimeters or even more before plant. In other words, the mechanism of this development of the tip occurs. When the physiological correlation appears to possess at length of 2 to 3 centimeters of a growing least certain of the characteristics of a transrunner is kept at a temperature of 3° to 4° C., missive or conductive, as distinguished from a development of the new plant usually begins purely transportative mechanism. within two to four days, and very little fur

C. M. CHILD, ther growth in length of the runner occurs,

A. W. BELLAMY even though its length is much less than the normal length of runner produced by the same

SCIENTIFIC EVENTS plant. Since each plant produces numerous

THE BRITISH NATIONAL PHYSICAL LABORArunners in succession, and since the normal

TORY length of runner at any given time. is very Sir RICHARD GLAZEBROOK, as already recorded definite, several runners, of both earlier and

in SCIENCE, resigned the directorship of the later origin than the experimental runner and National Physical Laboratory, Teddington, from the same plant, may be used as controls.

which he has held since its inception in 1899 There is no wilting of the runner distal to the

on September 18, his sixty-fifth birthday. low temperature zone, and the tip evidently

Sir Richard was principal of Liverpool Unireceives nutrition, for the growth and develop versity when he received the appointment to ment of the new plant take place as rapidly

the laboratory, which was founded by the as in normal runners which have attained Royal Society, and was originally intended as their full length. It should be noted, more

an extension of Kew Observatory. When the over, that these runner-tips are not permitted

new buildings were opened at Teddington in to touch the ground and become rooted, but

1902 it had but two departments and a staff of are kept suspended in air.

twenty-six. At the present time the staff numWork with this method is being continued

bers about 600, and building operations are and further results will be reported and ap

still in progress for the accommodation of new paratus and technique more fully described in

departments in research work. later papers. The results already obtained,

As already announced Richard Glazebrook together with certain conclusions to which

is succeeded by Professor Petavel, professor of they point are summarized as follows: first,

engineering and director of the Whitworth the inhibiting action of the growing tip of the

Laboratory in the University of Manchester. plant upon other buds, or of a leaf upon buds

The London Times writes: on other leaves, as in Bryophyllum, can be blocked by a zone of low temperature which

Sir Richard Glazebrook, who retires from the does not prevent the flow of water and nutri

directorship of the National Physical Laboratory,

has controlled its fortunes from its small begintive substances; second, the block produced

nings in 1899 to its present great place in the by the zone of low temperature does not in

scientific organization of the nation. It was first volve any visible or permanent alteration of

intended merely to carry out investigations rethe tissues, but is wholly reversible; third, a

quired in connection with the manufacture and temperature which is at first an effective block

testing of instruments of precision, and in 1902, may become ineffective after a few days, be

when it was moved to new buildings at Teddingcause of acclimation of the cooled zone to that

ton, it had only two departments and a staff of temperature; fourth, in view of the above

twenty-six. It has now seven scientific departfacts it appears at least highly probable that

ments, a secretariat, and a staff of over 600 perthe inhibiting action of growing tip, a leaf, or These deal with heat, optics, acoustics and other active region of a plant, depends for molecular physics, with electricity, metrology, engiits passage om point point upon metabol

neering, metallurgy, the forms of ips and aerial ically active protoplasm, rather than upon machines, and aero-dynamics. It is the supreme


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