SUMMARY OF CURRENT RESEARCHES 



RELATING TO 



ZOOLOGY AND BOTANY 



(principally invertebrata and cryptogamia), 



MICEOSCOPY, Etc.* 



ZOOLOGY. 



VERTEBRATA. 

 a. Embryologry.t 



Cell-Cleavage and Phytogeny.}— Prof. E. B. Wilson has reprinted 

 his lecture on this subject delivered at Wood's Holl Marine Laboratory 

 in 1898. Its object is to prove that the different stages of cell-cleavage 

 display definite homologies in different forms, and illustrate what he 

 aptly calls " ancestral reminiscences." It has long been known that 

 the cleavage in Polyclades strongly resembles that in Annelids and 

 Molluscs ; but a great difficulty has been that, in spite of the similarities 

 in the cleavage, the resulting quartets give rise to different structures in 

 the different groups, this being especially the case with regard to the 

 inesoblast. Some part of the difficulty is, however, obviated by the 

 recent discoveries of Lillie, Conklin, the author, and others, which tend 

 to show that the mesoblast -bands of the annelid or gasteropod are not 

 represented in the polyclade, but are neomorphs which have more or 

 less completely replaced the ancestral mesoblast. The evidence for this 

 is discussed in some detail, and the author's general conclusion is that 

 during the process of cleavage there is illustration of " ancestral remin- 

 iscence" similar to that clearly manifested by such structures as the primi- 

 tive streak in the egg of a bird, and the yolk-sac in the mammalian egg. 



Centrosome and Chromosomes.§ — The late Mr. B. B. Griffin con- 

 ducted an elaborate series of researches on maturation and fertilisation 

 phenomena, with special reference to the centrosome and the process of 

 reduction, and his MS. has been published by Prof. E. B. Wilson, under 

 whose direction the work was carried out. The material consisted of the 



* The Society are not intended to be denoted by the editorial " we," and they do 

 not hold themselves responsible for the views of the authors of the papers noted, 

 nor for any claim to novelty or otherwise made by them. The object of this part of 

 the Journal is to present a summary of the papers as actually published, and to 

 describe and illustrate Instruments, Apparatus, &c, which are either new or have 

 not been previously described in this country. 



t This section "includes not only papers relating to Embryology properly so called, 

 but also those dealing with Evolution, Development, Eeproduction, and allied sub- 

 jects. 



X ' Cell-Lineage and Ancestral Eeminiscence,' Boston, U.S.A., 1899, 42 pp., 5 figs. 



§ Journ. Morphol., xv. (1899) pp. 583-634 (4 pis. and 2 fig*.). 



