ZOOLOGY AND BOTANY, HIOKOSCOPY, ETC. 193 



Myxine, the breeding season is within the coldest season of the year, 

 (c) In Bdellostoma the micropylar end of the vitelline membrane forms 

 an operculum, which separates readily from the rest of the capsule, and 

 would thus allow the escape of the embryo, (d) Mr. Cunningham then 

 describes Teleostean ova of undetermined species, brought from the 

 Gulf of Guinea by Mr. J. Kattray, and having filaments and vitelline 

 membrane closely resembling those of Myxine. 



Influence of Movement on Developing Eggs.* — Signor A. Marcacci 

 has experimented on the effect of movement on the developing eggs of 

 the fowl. During the period from 48-72 hours, at a temperature of 

 38° C, he moved them in various directions without any change 

 resulting. But during the first two days such movement produced 

 various abnormalities of thoracic wall, beak, claws, eyes, &c. 



Significance of Sexual Reproduction.! — Dr. B. Hatschek, in regard- 

 ing the significance of sexual reproduction, commences with assimilation, 

 which he looks upon as the most important and probably original of 

 vital phenomena. He afiirms assimilation to be the sole known mode of 

 producing fresh living substance. He supports his belief that in sexual 

 reproduction we must recognize a remedy against the action of injurious 

 variability by the experience of breeders that a certain degree of differ- 

 ence between the parent individualities is most favourable to the result 

 of a crossing. Such differences as are caused in the organism by the 

 external conditions of life would evidently be of no service in a sexual 

 reproduction. A disease which made its appearance in an individual 

 which propagated solely by gemmation would be inherited from genera- 

 tion to generation, and endanger the existence of the entire species. 

 Mingling of sexual products would give not merely the possibility, but 

 even the highest probability of a rectification such as can be obtained in 

 no other way, and in this power of rectification Dr. Hatschek finds the 

 chief use for the existence of sexually differentiated individuals. 



Inheritance of Acquired Characters.^ — Prof. W. Detmer contri- 

 butes some botanical facts to this now familiar discussion. As against 

 Weismann's position he emphasizes (1) the intimate influence of external 

 conditions upon the histology of the organism ; (2) the importance of 

 correlation whereby an influence saturates through the organism from 

 one part to another ; (3) the suggestiveness of the persistence of 

 phenomena (like geotropism, photo-epinasty, periodicity of sap-flow) 

 after the inciting conditions have ceased. 



Ancestry of Man.§ — Prof. B. Wiedersheim gives a most interesting 

 and exhaustive account of the structures in the human body, which 

 afford testimony of ancestral features. He devotes a hundred pages to a 

 detailed discussion of the different systems, noting the points of interest 

 which have been demonstrated in regard to each. He then distinguishes 



(1) progressive changes, towards further differentiation (9 cases) ; 



(2) retrogressive changes, in which the organs in question still retain 

 functionality (12 cases) ; (3) retrogressive changes, in which the organs 

 in question, either in fcetal or adult life, either constantly or occasion- 



* Arch. Ital. Biol., ix. (1887) p. 58. 



t Ann. and Mag. Nat. Hist., i. (1888) pp. 163-4. See Prager Mediz. 

 Wochenschr., No. 46 (1887). 



% Arch. f. d. Gesammt. Physiol. (Pfluger), xli. (1S87) pp. 203-15. 

 § Ber. Naturf. Gesell. Freiburg i. B., ii. (1887) pp. 1-114. 



