;yS 



NATUR/i 



[January 16, 1919 



common in several districts of Macedonia. (13) Of 

 the tropical diseases which are of rarer occurrence in 

 the Balkans may be mentioned blackwater fever, 

 tilariasis, leprosy, sprue, intestinal myiasis, mycotic, 

 spirochaetic, and flagellate erethritis. (14) Certain 

 tropical skin diseases are frequently met with. 



Aristotelian Society, January 6.— Prof. Wildon Can 

 in the chair. — C. D. Broad ; Mechanical explanation 

 and its alternatives. Controversies between mechanis- 

 tic and non-mechanistic biologists suffer from a lack 

 of clear definition of what the opponents mean by 

 mechanism. The case is also prejudiced by confin- 

 ing the controversy to biology, and not raising the 

 same question about chemistrj ami other advanced 

 sciences. Mechanism must mean at least obedience to 

 the laws of motion 01 some substitute which reduces 

 indefinitely near to them for moderate velocities. This 

 condition is summed up by the form of Lagrange's 

 equations and the form of the function T and the 

 nature of the variables in it. Hut this is never a 

 sufficient condition of mechanism; for it leaves open 

 to the right-hand side of Lagrange's equations all 

 sorts of forms and all sorts of variables. According to 

 the different limitations imposed on their functions 

 and their variables, different senses of mechanism 

 emerge. Five senses are distinguished; the two leasl 

 rigid are macroscopic, the remaining three are micro- 

 scopic, in Lorentz's sense of these words. If the more 

 rigid forms hold at all, thev must hold microscopicallv, 

 for it is certain that thev do not hold macroscopicallv. 

 Microscopic explanations need not be mechanistic. 

 Only the less rigid forms of mechanism are necessary 

 for scientific explanation, and they are not necessary 

 for any profound metaphysical reason, but because 

 we can accuratelv measure only directly geometrical 

 magnitudes, and we cannot deal with a multitude of 

 complex and irreducible laws. Even the most rigid 

 form of mechanism might, however, be true if we 

 carry our microscopic analysis further than it has yet 

 been carried. The main advantage of pure mechanism 

 would be a unification in our theories of Nature. 

 Without it science is perfectly possible, but will take 

 the form of a hierarchy of laws of various degrees of 

 generality ; the more special of these will not be 

 deducible from the more general. When account is 

 taken of secondary qualities it is seen that pure 

 mechanism cannot be the whole truth even about the 

 non-mental part of the world. There is no necessary 

 conflict between teleology and mechanism; and the 

 ultimate cause of the special structure of teleological 

 systems is inexplicable with or without mechanism. 



Optical Society, January 9. — Prof. F. J. Cheshire in 

 the chair.- I.t.-Col. Williams: Design and inspection 

 of certain optical munitions of war. Service instru- 

 ments must be much more robust than those used by 

 civilian;, and have certain parts interchangeable. \s 

 regards optical systems, the definition is tested by 

 means of plates having round and square holes and 

 radiating grooves cut in them ; the magnification by 

 means of ,-i dynameter; the field of view and spacing 

 of graticules by means of scales; the normal focus by 

 means of an auxiliary telescope; the diopter scales by 

 means of standard lenses, etc. Much trouble has been 

 experienced due t<> lenses, prisms, etc., in enclosed 

 instruments having become filmy after a time. 



Dublin. 

 Royal Dublin Society, December 17, 1918. — Prof. 

 G. H. Carpenter in the chair.- Dr. Joseph Reilly and 

 VV. Hickinbottom ; Determination of the volatile fatty 

 acids by an improved distillation method. Assuming 

 Nernst's law"" of distribution, the theory of distillation 

 of a dilute aqueous solution of a volatile substance 

 \n. 2568. VOL. T02~| 



has been considered. The distillation constants of 

 Naumann and Midler, Stein, and others base been 

 correlated, and it is demonstrated that they are 

 depi ndent on Nernst's law. The lower fatty acids 

 wen- taken as a type of volatile substances soluble 

 in water, and comparative distillation constants both 

 for single acids and mixtures of acids have been deter- 

 mined. The apparatus used was of an improved 

 type, in which the distillation was carried out at con- 

 stant volume, the whole apparatus being steam- 

 jacketed. Water was added through a side tube 

 sealed into a quartz distillation flask at a point below 

 the surface of the solution. A comparison was made 

 with the methods employed by Duclaux, Dyer, and 

 Stein. It is shown experimentally that the distilla- 

 tion constanl is inversely proportional to the volume. 

 It is also observed that there is a relation between 

 the distillation constants and the molecular weight. 

 From an examination of the percentage of acid dis- 

 tilled over in each fraction, from solutions of mixtures 

 of two or three fatty acids, it is shown that the 

 composition of the original mixture can be calculated 

 with a fair degree of accuracy, thus affording an 

 experimental verification of Nernst's law. This 

 method of distillation is capable of being exti 

 to the distillation of substances other than the lower 

 fatt\ aude Mi.s Margaret C Fload : I lie exuaat; n 

 of water from the leaf-tips of Colocasia antiquoriim. 

 Under normal conditions the leaf-tips of this spi 

 emit a succession of drops of liquid water (10-120 to 

 the minute). In view of the extreme purity of the 

 water expelled, as shown by cryoscopic and conduc- 

 tivin tests, the mechanism of the secretion and filtra- 

 tion is of interest. It has been generally supposed 

 that a gland at the leaf-tips is responsible for the 

 exudation, but minute microscopic investigation has 

 shown that no such gland is to be found in the leaf- 

 tip, and this histological evidence is confirmed by 

 experiments in which colloids have been induced in 

 flow through the tips, thus physically demonstrating 

 a continuous passage from the water channels in the 

 leaf through the tips. Hence we must assume that 

 the exuded water is raised and filtered by the activity 

 of tissues lower down in the plant. — Dr. G. H. 

 Pethybridge : Preliminary note on the possibility of dis- 

 tinguishing the seeds of wild white clover from those 

 of ordinary white clover by chemical means duri 

 germination test. Mirande showed that Trifolittm 

 repens contained a cyanophoric glucoside. H. £. and 

 E. F. Armstrong and E. Morton -found that traces 

 of HCN could be detected in the green cotyledons of 

 young seedlings derived from the seed of wild white 

 clover even on the fourth or fifth day after germina- 

 tion, but not in plants raised from ordinary or "cul- 

 tivated" seed at any stage of growth. It was there- 

 fore thought that by using Guignard's alkaline picrate- 

 paper it might be possible to distinguish the seedlings 

 of wild white clover from those of ordinary clover 

 with certainty during a germination test. Extended 

 trials showed, however, that the seedlings from wild 

 white clover-seed were not alone in giving a positive 

 reaction for HCN, but that seedlings raised from 

 commercial varieties of ordinary white clover-seed of 

 American and Canadian origin also gave a positive 

 reaction. Hence this reaction cannot be regarded as 

 infallible as a means of differentiating betwi 1 n 

 ordinary and wild white clover-seeds. — E. J. Sheehy : 

 Possible causes of variation in the quantity and quality 

 of cow's milk. An account is given of experiments 

 conducted in 1918, supplemental to the earlier work 

 of 1915 and icpfi. One experiment shows that the 

 proportion of solids not fat in milk decreases from 

 the fir^t sample drawn at a milking to the "strip- 

 pings," while the percentage of fat increases. The 



