286 



SUMMARY OF CURRENT RESEARCHES RELATING TO 



Life-History of Monocystis ascidise.* — M. Siedlecki has worked 

 out in detail the following summary of the life-history of this species : — 



Sporozoite 



mature individual 



Sporozoite 



mature individual 



conjugation 

 n sporoblasts n sporoblasts 



>' 



copulation 



- 



n sporocysts 



8 n sporozoites 



Influence of Gregarines on the Cells of their Host.f — Michel 

 Siedlecki adduces a number of facts, especially with reference to Mono- 

 cystis ascidise Lank, (which passes most of its growth-period within a 

 cell of the intestinal epithelium), showing that the parasite has at first 

 a hypertrophic influence on its cell-host. The influence is probably 

 chemical, and due to excretory products passing from parasite to host. 



Asexual Multiplication of Gregarines. J — Maurice Caullery and 

 Felix Mesnil, in discussing this, begin by pointing out that the life- 

 cycle of Coccidia is now fairly clear : — intracellular asexual multiplica- 

 tion (schizogony, with merozoite-stages) ; growth and differentiation of 

 male and female gametes; "heterogonic" conjugation, leading on to the 

 formation of sporoblasts, and thence from sporocysts to sporozoites 

 (" sporogony "). The whole period of the growth of the asexual elements 

 and of the gametes is intracellular. 



In Gregarines there is much greater diversity, from entirely extra- 

 cellular development to a growth almost completely intracellular (Mono- 

 cystis ascidise, &c), with possible intracellular schizogony. From the 

 last state of affairs, illustrated by Gonospora longissima, there is an 

 approximation to what occurs in Coccidia, in which the growth is 

 wholly intracellular, and schizogony is general. But in Coccidia 

 heterogamy has replaced isogamy. 



The authors direct attention to the hypertrophic influence exerted 

 by Gregarine parasites on their cell-hosts. 



Plistophora mulleri (L. Pfr.).§ — Dr. W. Stempell has studied the 

 microsporidium found by L. Pfeiffer in the muscles of Gammarus pulex, 

 and described under this name by him. Stempell has been able to 



"* Bull. Acad. Sci. Cracow, December 1899. 

 Arch. Zool. Expe'r., viii. (1900) pp. lx.-lxii. 



t Comptes Rendus, cxxxii. (1901) pp. 218-20. 

 § Zool. Anzeig., xxiv. (1901) pp. 157-8. 



See O. Dubosq, Notes et Revue, 

 t Tom. cit., pp. 220-3. 



