260 SUMMARY OP CURRENT RESEARCHES RELATING TO 



is always circular apparently, but probably it is much flattened; 

 during the first half of karyokinesis it remains round, or becomes 

 oval ; its long axis, however, is not congruent with the axis of division, 

 and is often, indeed, quite at right angles to it. Later on, a con- 

 striction appears in the nucleus, which deepens till at last the two 

 daughter-nuclei are only connected by a thin filament, which breaks 

 later. The nucleoli disappear gradually, and do not pass directly 

 into the chromatic figure. It is important to note that in the 

 daughter-nuclei they are separate from the chromatic figures. 



It is clear, then, that in all essential points the process of nuclear 

 division in Opalina is the same as in Amphibia and Mammalia, and 

 such differences as there are are merely quantitative. 



The question arises whether this may be made a generalization 

 for all Protozoa ; but it is one that cannot yet be certainly answered ; 

 it is very probable that it is so, and that is all that can be said at 

 present. 



Glycogen in Ciliated Infusoria,*— M, E. Maupas, referring to 

 the doubt expressed by Prof, Biitschli as to the presence of glycogen 

 in ciliated Infusoria, gives an account of some experiments by which 

 he hopes he has demonstrated the presence in these Infusoria of a 

 substance exactly comparable to the glycogen of higher animals. 



Dialytic Properties of the Membrane of the Cyst of Infusoria.f 



— ^M. Fabre discusses the question of the function of the membrane 

 of the cyst which forms around some Infusoria, such as Goljpoda or 

 Vorticella nehulifera, and comes to the conclusion that the membrane 

 is really chitinous, is perfectly porous, and at the same time exhibits 

 special elective properties for the passage of certain bodies ; neutral 

 salts pass through it less easily than acid solutions, and it thus delays 

 or prevents the death of the individual from the possible concentration 

 of the water in which it lives. 



Temporary Encystment among Infusoria.| — Mr, J, G. Grenfell 

 records some observations on some hypotrichous infusoria, amongst 

 which were a niunber of Sphserophrya. He found that when an in- 

 fusorian was attacked by a Sphserophrya, it drew in its cilia, and 

 commenced to form a cyst, at the same time allowing a small part of 

 its protoplasm to burst. The infusorian would endeavour to leave 

 the cyst, but withdrew back into it, if Sphserophrya was still present. 

 Sometimes the animal leaves the cyst, on the side opposite to the 

 Sphserophrya, as a motionless oval body instead of having the shape 

 it usually has on leaving an ordinary spiked cyst, which is formed 

 when the pond, &c., is drying up. 



Ectoparasitic Peritrichous Infusorian.§ — Dr. E. Blanchard de- 

 scribes Apiosoma piscicola, a new genus and species of ectoparasitic 

 peritrichous infusorians which he found, especially on carp, in the 

 fresh-water aquaria at Havre. The body is pyriform, and is attached 

 to the surface of the epidermis of the fish by a kind of non-contractile 



* Comptes Rendus, ci. (1885) pp. 1504-6. f Ibid., pp. 1507-9. 



X Science-Gossip, 1886, pp. 31-3. 



§ Bull. Soc. Zool. France, x. (1885) pp. 277-80 (1 pi.). 



