168 SUMMARY OF CURRENT RESEARCHES RELATING TO 



understanding all of the forces that influence the phenomena of pro- 

 toplasm." 



Conversational .Etiology.* — Franz Krasan discusses by means of 

 imaginary conversations between half a dozen incognitos the pro- 

 foundest questions of biology : — How far is organic form a function 

 of organic substance ? What is the nature of reaction to environment ? 

 Can we distinguish between the original and the accessory characters of 

 individuals ? What is the real meaning of metamorphosis and sub- 

 stitution of organs ? What is the evolutionary import of variation, 

 mutation, and modification ? How are we to define species, variety, 

 and breed ? What is the scope of hybridisation and in-breeding, of 

 isolation and selection ? The author traverses the whole field of evolu- 

 tion-theory, but his peculiar mode of presentation is not attractive. 



Uterine Implantation of the Ovum of Spermophilus citillus.f— 

 J. Rejsek shows that the first fixation and preliminary nutrition of the 

 ovum in this mammal is quite apart in time and space from the placental 

 fixation and nutrition. Fertilisation and cleavage occur in the Fallopian 

 tube, and the segmented ovum passes into the uterus. A portion of the 

 superficial stratum (Rauber's layer) remains composed of high cells, 

 while the rest of the cells of this stratum are flattened. The high cells 

 form a thickening at the pole opposite the blastodermic disc, and give 

 rise to a syncytial prominence which enters into close connection by 

 means of processes with the wall of the uterus. Details of the growth 

 of these syncytial processes are given ; they degenerate as the placenta 

 develops. 



For a very short time the ovum depends on itself, but there is soon 

 need for maternal nutrition. This is provisionally afforded by the pro- 

 cesses of the syncytium, which establish a nutritive connection between 

 the ovum and a fluid material for the most part derived from the 

 maternal uterine cells. 



Normal Degeneration of Eggs not Liberated. £ — M. Dubuisson 

 corroborates and extends the observations of C. Perez on the degenera- 

 tion of unlaid eggs. His material was found in the eggs of sparrow, 

 frog, and newt. He describes the part played by follicular cells and by 

 phagocytes. 



Spermatozoa of Discoglossus pictus.§ — E. Ballowitz gives a de- 

 tailed description of the unique spermatozoa of this amphibian. They 

 are remarkable (1) in their extraordinary length (2|- mm.) ; (2) in the 

 elaboration of screw-architecture in all the parts ; and (3) in the fine 

 details of their structure. 



Correlation between Poison-Gland and Ovary in Toad.|j — C. 

 Phisalix notes that the poison-gland of the female toad is almost empty 

 at the spawning time, and in striking contrast to that of the male. He 

 finds that the active principles of the poison are present in the eggs, 



* Ansicbten und Gespr'ache iiber die individuelle und specifiache Gestaltung in 

 der Natur. 8vo, Leipzig, 1903, vii. and 280 pp. 



t Arch. Mikr. Anat., lxiii. (1903) pp. 259-73 (1 pi.). 

 X Comptea Rendus, cxxxvi. (1903) pp. 1690-1. 

 § Arch. Mikr. Anat., lxiii. (1903) pp. 343-64 (1 pi.), 

 if Comptea Kendus, cxxxvii. (1903) pp. 1082-4. 



