August i8, 1923] 



NA TURE 



25. 



of radiation source became an important considera- 

 tion. 



The social , aspects of tuberculosis were discussed 

 in this Section as well as in that of Public Health. 



A large exhibition was organised representing 

 practically every aspect of medical work. This was 

 supplemented by additional exhibits of interest to 

 special Sections, such as radiology, pathology, 

 parasitology, anatomy, etc., but considerations of 

 space do not allow of more detailed notice here. 



The meeting was very largely attended. The work 

 of the local committees resulted in a very wide choice 

 of excursion to the visitors, which was highly appreci- 

 ated by them. 



Einstein and the Philosophies of Kant 

 and Mach. 



'T'HE Bulletin de la Societe Franfaise de Philosophie 

 -*■ for July 1922, which has just been published 

 (Armand Colin, Paris), contains the report of the recep- 

 tion of Prof. Einstein in Paris on April 6, 1922. It is 

 B of exceptional interest, for Einstein did not make an 

 ^ original communication, but assisted at a discussion 

 of the theory of relativity. 



Prof. Langevin introduced the discussion, and 

 Messrs. Hadamard, Cartan, Painleve, Perrin, Becquerel, 

 Brunschvicg, Le Roy, Bergson, Meyerson, and Pieron 

 took part. It elicited from Einstein two pronounce- 

 ments of special significance in regard to the 

 relation of his theory first to Kant and secondly 

 to Mach. We quote them in full. The first was 

 in reply to M. Brunschvicg, who had said that 

 the Kantian philosophy in separating a container, 

 space and time, from a content, matter and force, 

 had ended in antinomies, while Einstein's con- 

 ception, which is characterised by the fact that 

 container and content are inseparable, had delivered us 

 from them. To this Einstein replied : " I do not 

 think my theory accords with the thought of Kant, 

 that is, with what that thought appears to me to be. 

 What appears to me the most important thing in 

 . Kant's philosophy is that it speaks of a priori con- 

 cepts for the construction of science. Now there are 

 two opposite points of view : Kant's apriorism, 

 according to which certain concepts pre-exist in our 

 consciousness, and Poincare's conventionalism. Both 

 agree on this point, that to construct science we need 

 arbitrary concepts ; but as to whether these concepts 

 are given a priori or are arbitrary conventions, I am 

 unable to say." 



The second pronouncement was in reply to 

 M. Meyerson, who had challenged him to declare 

 how far he was in agreement with the theory of 

 Mach. Einstein replied : " There does not appear 

 to be a great relation from the logical point of view 

 between the theory of relativity and Mach's theory. 

 For Mach, there are two points to distinguish : on 

 one hand there are the immediate data of experi- 

 ence, things we cannot touch ; on the other there are 

 concepts which we can modify. Mach's system 

 studies the existing relations between data of experi- 

 ence ; for Mach, science is the totality of these 

 relations. That point of view is wrong, and, in fact, 

 what Mach has done is to make a catalogue, not a 

 system. To the extent that Mach was a good 

 mechanician he was a deplorable philosopher. His 

 view of science, that it deals with immediate data, 

 led him to reject the existence of atoms. Probably 

 were he still with us he would change his opinion. I 

 would like to say, however, that on the other point, 

 namely, that concepts can change, I am in complete 

 agreement with Mach." 



The Life-Cycle of the Protozoa. 



pROF. C. A. KOFOID delivered, on December 27 

 -"- last in Boston, an address as vice-president of 

 Section F (Zoology) of the American Association for 

 the Advancement of Science and as president of the 

 American Society of Zoologists, on the life-cycle of 

 the Protozoa [Science, vol. Ivii. pp. 397-408, April 6, 

 1923). He remarked that the striking similarities 

 of the most ancient fossil Protozoa to recent afford 

 some ground for the inference that the Protozoa living 

 to-day differ but little from those when life was young. 

 A consideration of the accounts of the origin de novo 

 of nuclei from chromidia leads to the conclusion that 

 adequate evidence of such origin is lacking. Prof. 

 Kofoid holds that, as sound cytological investigation 

 of the Protozoa progresses, it becomes increasingly 

 evident that the descent of the nuclei and the in- 

 dividuality of the chromosomes, found in the Metazoa, 

 holds also for the Protozoa, and it may be inferred 

 that the Protozoa are equipped with the essential 

 structural basis — chromosomes and mitosis — for the 

 mechanism of heredity. 



The searcher for the origins of biological phenomena 

 finds in the Protozoa a fertile but perplexing field. 

 Here have arisen all the fundamental types of 

 symmetry — spiral, leiotropic, dexiotropic, radial, 

 bilateral, and modifications of these. Here also are 

 several distinct types of mitosis, different locations 

 of the centrosome, and extraordinary derivatives of 

 this organ ranging from the nematocysts of Dino- 

 flagellates to the complicated neuromotor system 

 of the trichonymphid flagellates. Sex and sexual 

 dimorphism have also had their origin in the Protozoa. 

 Prof. Kofoid also refers to the universal occurrence 

 of asexual reproduction in the Protozoa, and to the 

 development after fertilisation of a multicellular 

 stage, which he terms a somatella, in which there is 

 generally no progress to the point of division of labour 

 and differentiation of tissues, although the differentia- 

 tion of sexual and somatic cells occurs in some cases, 

 e.g. Volvox. The sequence of events within the cyst 

 of Entamoeba — involving elaboration of glycogen 

 and the formation of the chromatoidal substance 

 with its relation to the growth processes — is regarded 

 as suggestive of the sequence in the egg and of the 

 relationship t)f specific yolk substances to cleavage 

 and differentiation in the metazoan egg. The obser- 

 vations of Jameson on maturation in the Sporozoa 

 show that the haploid condition persists throughout 

 the period of growth and asexual reproductions, while 

 the diploid lasts but one cell-generation. Such 

 conditions give occasion to wonder whether or not 

 sexual reproduction may not have been elaborated 

 gradually and independently within widely different 

 groups in the Protista, and - afterwards in them 

 and in higher forms of life the diploid state has 

 extended its domain more and more throughout the 

 life-cycle. 



Prof. Kofoid considers that the life-cycle of the 

 malaria parasite — the zygote, the multicellular stage 

 which follows and leads to the formation of sporo- 

 zoites, which on introduction to man undergo growth 

 and asexual reproduction to form merozoites, and 

 the eventual production of gametocytes — may be 

 compared with the fundamental processes of fertilisa- 

 tion, cleavage, asexual reproduction, and gameto- 

 genesis in the Metazoa, except that histogenesis and 

 organ differentiation do not appear. He believes it 

 may perhaps be helpful and serve to facilitate progress 

 if we emphasise the similarities of organisms and seek 

 to find the common processes underlying them all, 

 rather than to emphasise their differences and thus 

 obscure our vision of fundamental problems of life. 



NO. 2807, VOL. 112] 



