2l8 



NATURE 



[January 5, 1905 



The present books furnish abundant proof that this 

 statement is particularly applicable to the Zeiss instru- 

 ments in regard to the quality of those materials most 

 essential for the production of good optical apparatus, 

 viz. brains and know ledge of advanced mathematics. 



G. H. Bry.an. 



AUEmCAl^ CYTOLOGY. 

 Fecundation in Plants. By David M. Mottier, Ph.D. 



Pp. viii+187. (Washington: Published by the 



Carnegie Institution, 1904.) 

 Contributions to the Knowledge of the Life-History of 



Piniis, with Special Reference to Sporogenesis, the 



Development of the Gametophytes and Fertilisation. 



By Margaret C. Ferguson, Ph. D. Pp. 153. 



(Washington : Published by the Washington 



Academy of Sciences, 1904.) 



MR. MOTTIER'S " Fecundation in Plants " gives 

 to those who are interested in cytology an 

 account of the phenomena of fertilisation throughout 

 the vegetable kingdom, written by one who has carried 

 on investigations in several branches of the subject with 

 success. His practical acquaintance with his subject 

 confers even on his descriptions of the investigations 

 of others a freshness which makes his work a pleasure 

 to read. The first chapter is perhaps the most generally 

 interesting. In it he gives an account of some of the 

 vexed problems of karyology which are at present 

 calling out so much controversy among cytologists. 

 Among these problems may be mentioned the e.xistence 

 of centrosomes, the homology of centrosomes and 

 blepharoplasts, the nature of synapsis, the significance 

 of the se.xual process, and the numerical reduction of 

 chromosomes. The author's method of discussion is 

 candid. He avoids being dogmatic in expressing his 

 own views, although he criticises somewhat severely 

 the observations of others. He holds that centrosomes 

 and centrospheres do not occur in plants higher than 

 the liverworts, and are, indeed, only well established 

 in a few of the Thallophyta. It is remarkable that 

 he does not allude to the possibility that the radiations 

 at the poles of mitoses may be in part artefacts pro- 

 duced by the fixing agents. He considers Belajeff 

 hasty in coming to the conclusion that the centrosome 

 is the homologue of the blepharoplast ; but he admits 

 later on that certain " facts lend encouragement to 

 the belief that centrosome and blepharoplast may be 

 homologous structures." Mottier regards synapsis 

 as due in a large measure to the action of reagents. 

 He accepts Strasburger's theory of the numerical 

 reduction of chromosomes as a good working hypo- 

 thesis, and he holds now that there is no evidence for 

 Weismann's " reduction " to be found in the mitoses 

 of plants. His candid expression of doubt as to the 

 persistent individuality of the chromosomes preserved 

 through the successive mitoses — so often assumed, 

 though almost involving a miraculous resurrection — is 

 typical of his attitude of independence. 



The succeeding chapters give an account of fertil- 

 isation in types taken from the various subdivisions 

 of the vegetable kingdom. These descriptions are 

 most useful in bringing together what is scattered 

 NO. 1836, VOL. 71] 



sporadically through botanical literature into the 

 compass of a short, well written book. The work is 

 illustrated by blocks in the text, which show in a 

 satisfactory manner the points to be brought out. 



Miss Ferguson's memoir has a more limited scope, 

 but this allows her to devote more space to her own 

 researches, which have been very extensive in the 

 cytology of the spore-production of conifers. It is 

 quite remarkable to see how two cytologists, writing 

 almost simultaneously, can hold so divergent views on 

 fundamental subjects. While Mottier sees in the 

 fusion of sexual nuclei the blending of two lines of 

 descent, Miss Ferguson's researches lead her to believe 

 that no fusion-nucleus, combining the paternal and 

 maternal hereditary substances, is formed. Rather 

 the processes of 'mitosis allow these to be kept apart 

 during the life of the offspring, and the " reduction " 

 or qualitative division occurring some time during the 

 life-cycle secures that the gametes shall be "pure." 

 It is evident that the later writer is concerned with 

 the relation of mitosis to Mendel's views rather than 

 to Weismann's hypothesis. With regard to synapsis. 

 Miss Ferguson believes it to be a normal stage in 

 heterotypic mitosis. Another point of difference is the 

 mode of origin of the double chromosomes of hetero- 

 typic mitosis. Miss Ferguson finds confirmation in 

 her preparations for the view (first published by the 

 writer of this review in 1896, Proc. Roy. Irish Acad.) 

 that the two arms of the chromosomes are approxi- 

 mated pieces of the nuclear thread, and do not arise by 

 longitudinal cleavage as Mottier believes. This inter- 

 pretation seems to be gaining ground, and the Louvain 

 school, once so much opposed to it, has recently 

 accepted it, putting the folding back, however, to the 

 synaptic stage. The reviewer's investigations seem to 

 suggest the possibility that two distinct foldings take 

 place, one during synapsis and another between that 

 stage and the differentiation of the chromosomes. 

 Whatever views are held on these disputed matters, 

 all cytologists are indebted to the author for her 

 beautiful drawings, which are reproduced in a series 

 of twenty-four plates. 



There is no doubt that the publication of these two 

 memoirs, the one by the Carnegie Institution and the 

 other by the Washington Academy, will be of much 

 service to those engaged in cvtological research. 



H. H. D. 



PHYSIC.-iL RESEARCH AT LEYDEX. 

 Het Xatiturkundig Laboratoriunt der Ryks-litiversi- 

 teit te Leiden in de Jaren 1882-1904. Gedenkboek 

 aangeboden aan den Hooglceraar H. Kamerlingh 

 Onnes, Directeur van het Laboratorium, by gelegen- 

 heid van zyn 25-jarig Doctoraat op 10 Juli 1904. 

 Pp. viii + 288. (Leyden : Eduard Vdo, 1904.) 



THIS volume was prepared by colleagues and pupils 

 of Prof. Kamerlingh Onnes, of Leyden Uni- 

 versity, and presented to him on the twenty-fifth 

 anniversary of his receiving the degree of Ph.D. It 

 differs in character from the usual collections of 

 scientific papers which it has become the fashion on 

 the Continent to present to eminent men of science on 



