August 28, 19 19] 



NATURE 



517 



\\ Fireclays can be rendered more plastic and more 

 fractory by this treatment. 



Another very important application of cataphoresis 

 - the electrical filter-press. In this press the elec- 

 ical potential is utilised as a means of driving out 

 he water from suspensions of fine particles; thus, 

 instead of needinjr pressures running up to 20 atmo- 

 spheres in some cases where ordinary filtration is used, 

 head of 14 ft. is ample for the purpose in the elec- 

 ical filter-press. As an instance of the efficiency and 

 peed with which filtering can be accomplished by 

 iich a press, a cake of china clay 4^ in. thick con- 

 lining 25 per cent, of water can be made in less than 

 wo hours. 



The applications of electrical endosmose or electrical 

 dialysis in various industries is of importance. Gela- 

 tine can be freed from all inorganic mineral matter, 

 so that an ashless gelatine can be obtained of a purity 

 which should be suitable for photographic purposes. 

 There is clear experimental evidence that pure col- 

 loidal silicic acid can be prepared from sodium silicate 

 and alumina from sodium aluminate by subjecting 

 their solutions to rn electrical potential in cells with 

 suitable diaphragms through which the alkali can 

 migrate. These are a few examples of useful develop- 

 ments, but it is evident that an increasing number of 

 important commercial processes may be expected to 

 arise out of the application of the principles under- 

 lying the above phenomena. 



EVOLUTION IN POTATO-BEETLES.-^ 



■pjR. W. L. TOWER has continued his attack on 

 -*-' the "evolution problem" by a further study of 

 Chrysomelid beetles of the genus Leptinotarsa. He 

 first gives an account of the material as it occurs in 

 natural conditions ; he then describes the emergence 

 of new attributes and qualities, discovering the rela- 

 tion of these to old characters and their interaction 

 when brought into combination or into competition 

 with existing characters ; and, thirdly, he has experi- 

 mented in Nature, chiefly in the Arizona deserts, with 

 the new forms to see how newly arisen characters, 

 or their combination into specific forms, behave as 

 they meet the conditions of the environment into 

 which they are thrust by the processes of their 

 origination. His most general result is the demon- 

 stration that the methods of evolution are hetero- 

 geneous, even in these beetles, but " the basis of all 

 methods of change is found to be directly the product 

 of the nature of the genetic factors of composition and 

 their capacity for diverse modes of reaction, especially 

 with factors of the environing complex. Purpose, 

 utility, and kindred concepts have found no support, 

 every change appearing as the chance mechanistic pro- 

 duct of the reacting agents ; while the product of the 

 reaction either was able or not able to operate under 

 the conditions of origination, so that survival is decided 

 at once, and not after long and faltering trials." 



The characters of organisms are usefullv grouped 

 under three chief categories : — (i) The specific proper- 

 ties or qtialities which cannot be altered without 

 change in the identity of the kind ; (2) attributes 

 belonging to and distinguishing members of the same 

 species or kind from one another ; and (3) conditions 

 or " states of being or activity which can be changed 

 or removed without altering the identity of the body 

 or its kind in anv way." The central problem of 

 evolution is the origin of diversity or heterogeneity, 

 and Dr. Tower distinguishes two main possibilities : 

 " first, transmutation in the qualities with subsequent 

 adjustments in the attributes and conditions of 



1 "The Mechanism of Evolution in Leptinotarsa." By WHIiam Lawrence 

 Tower. _ (fubl'cation No. 26:1.) Pp. 340+19 PU. + 156 figs. (Carnegie 

 nstitution of Washington, 1918.) 



NO. 2600, VOL. 103] 



organisms ; and, second, diversity resulting from re- 

 combinations (metathesis)." The gametic constitu- 

 tion or hereditary make-up of the organism consists 

 of a number of factors (neither "carriers" of any- 

 thing, nor fixed units, nor necessarily substances, but 

 agents or centres of activity which make certain 

 results possible) and of a number of determiners 

 which settle which of several possible reactions will 

 come off. " In Nature there is constant and un- 

 limited mixing of these factors and determiners in all 

 kinds of combinations ; but out of this complex of 

 interacting agencies certain definite patterns always 

 come, so that the net result is a rather stable popula- 

 tion as far as the patterns presented in any given 

 location. The heterogeneity presented, however, is 

 not one of quantity nor of directions of departure, but 

 is at least analogous to the diversity found in many 

 chepiical operations where nearly related compounds 

 are easily transmuted into some other through the 

 presence or absence of something whose presence 

 determines a different configuration of the system, 

 and whose absence permits of another and diverse 

 arrangement." The pattern on the beetle's pronotum 

 is, in its way, an intricate system, and the presence 

 of certain form-determiners decides the type. Thus, 

 if we generalise from the beetles, variation is not so 

 much the origin of something distinctively new as a 

 shuffling of the pre-existing cards. It is recombination 

 or metathesis. "The phenomena must be viewed as 

 purely physical in character and of chance occurrence, 

 deperident upon chance gametic agents, combinations, 

 and conditions present, as far as their appearance and 

 frequency in Nature are concerned." But the system 

 in question (or any analogous set of characters), 

 "although complex "and the product of many inter- 

 acting agents, nevertheless acts as a unit in many 

 reactions, passing through the operations of repro- 

 duction and crof^sing in its entirety, or at other times 

 emerging from the reactions changed in relations and 

 arrangements of the elemental simplest characters, 

 indicating altered relations between the conditioning 

 agents." But when the further question is asked 

 how the populations of beetles in different locations 

 have become different. Dr. Tower confesses his in- 

 abilitv to give any answer. " I have most earnestly, 

 in this investigation, in numerous instances made 

 effort to certainly discover the productive agents of 

 conditions found in Nature . . . but in no instance 

 thus far have T been able to attain to the desired end 

 of a proof of the actual cause of the conditions 

 observed." 



We have not found the memoir very easy to read 

 (and our quotations will in part show why). We 

 think that the author might have focused more clearly 

 the new conclusions he has arrived at. But the 

 volume is the outcome of laborious investigations and 

 careful critical analysis; it is a fine example of the 

 modern transition from plausible speculations to the 

 verifiable exneriments. We are not so sure as the 

 author is that science is shut up to rrlechanistic 

 formulation ; and we should like to know how he 

 comes to be so sure that his beetles have no purposes. 

 We notice a few misprints like "Cu^rrot," but they 

 have, no doubt, arisen mechanically. 



UNIVERSITY AND EDUCATIONAL 

 INTELLIGENCE. 

 Mme. Curie has been appointed professor of 

 radiology in the Warsaw University. 



A SCHOLARSHIP of the value of 1200 rupees has been 

 0\ven to the Madras Medical College by Lt.-Col. 

 W. D. Smith for the benefit of students in chemistn.' 

 and drugs. 



