286 SUMMARY OF CUKRENT RESEARCHES RELATING TO 



spermatozoa in this Pteropod, and to the production of two kinds of 

 spermatozoa through the- unequal division of the heterochromosomes. 

 In the oogenesis there is a diminution of chromatin. In the develop- 

 ment of the young oocyte a diploid chromosome unites with the nucleolus. 

 Subsequently a portion of this chromosome is separated off and develops 

 further in the geiininal vesicle, just like, the other chromosomes. The 

 other portion remains attached to the nucleolus. In the formation of 

 the first maturation spindle the nucleolus, along with the associated 

 chromosome, is extruded into the ovum-cytoplasm and breaks up. Thus 

 there is in the course of oogenesis an actual diminution of chromatin, 

 for one chromosome loses half its mass. 



5. Lamellibranchiata. 



Experimental Metaplasmia in Pecten.* — The late G. Harold Drew 

 demonstrated the conversion of fibroblasts into ciliated epithelium. 

 When a piece of ovary is implanted into the adductor muscle of Pecten 

 O'percularis it becomes surrounded by a closed sac lined vvith layers of 

 fibroblasts. Complete degeneration and disintegration of the ovarian 

 tissue occurred in a few days. After the lapse of 21-32 days the mner- 

 most layer of fibroblasts reverted to an embryonic type, and afterwards 

 became converted into columnar ciliated epithelium which formed a 

 continuous layer lining the cyst. The changes resulting in this forma- 

 tion of ciliated epithelitim from fibroblasts were followed step by step. 

 The transformation was not produced by the implantation of any other 

 tissues of Pecten, or of neutral foreign bodies, or of ovarian tissue from 

 another bivalve, or of ovarian tissue of another species of Pecten : thus 

 it seems to be a perfectly specific reaction that occurs only when the 

 ripe living ovary of the same species is implanted. 



Details of the Nervous System of Anodonta cellensis.t — P. 

 Splittstosser gives a detailed account of the cerebral, pedal, and visceral 

 ganglia and their nerves, and the innervation of the mantle margin. 

 He calls attention to the constant and variable nerves, the variability of 

 the ganglia, the commissural connexions, the innervation of the 

 muscles and of the various organs of the body. Numerous new details 

 are brought out. 



Arthropoda. 



a. Insecta. 



Colouring of the Fatty Bodies in Larvae of Cionus oleus.if 

 A. Ch. Hollande finds that the larvte of this Curculionid beetle have 

 bluish-violet fatty bodies, and that this is due to an anthocyan ingested 

 from the young staminal hairs of Verbascum nigrum, among which the 

 creature lives. The larva is brownish-violet in colour, and the violet 

 hue is produced by the granulations in the fatty body shining out 

 through the brownish integument. In short, there is a " vital color- 

 ation " of the " pseudonuclei " of the cells of the fatty bodies. The 



* Journ. Exp6r. Zool., x. (1911) pp. 349-79. See also Jouru. Marine Biol. 

 Assoc, ix. (1913) pp. 572-4. 



t Zeitschr. wiss. Zool., civ. (1913) pp. 388-470 (19 figs.). 



X Arch. Zool. Exper., li. (1913) Notes et Revue No. 2, pp. 53-8. 



