GREGARINIDA 



be: encysted together, and in one species (Pyxinia jrenzeli} this is as frequent 

 as the encystment of two. 1 



The fusion is effected with synonymous layers, thus being different 

 from the above-mentioned association (adherence), which can always be 

 relinquished or broken up. 



Hitherto it has been inferred that the two encysted individuals (sporonts) 

 conjugate because, as a rule, they sooner or later merge into one another ; 

 this opinion is, moreover, supported by the statements of Wolters 2 and 

 Roboz, 1 the former believing that he has actually witnessed the fusion of 

 the nuclei of the two encysted individuals that sets in after the reduction 

 of the nucleated substance and the expulsion of one part, whereas the 

 latter has, at all events, observed the expulsion of portions of nucleus. This 

 latter phenomenon has also been confirmed by recent research 4 ; but, on the 

 other hand, this observation has by no means proved even transient union of 

 the reduced nuclei of the two sporonts, and accordingly there can be no 

 question of the conjugation of the two individuals encysted together ; their 

 large vesicular nucleus rather dissolves, the greater part disappears in the 

 substance of the body, or is sometimes ejected, and a new, though very small, 

 nucleus is formed of the residue, and divides mitotically. The daughter nuclei 



FIG. 22. Two so-called conjugation stages FIG. 23. Sporulation stage of 



of Clepsidrina blattarum. (After Biitschli). Clepsidrina ovata, schematised. 



(After A. Schneider.) 



divide again a circumstance we have long been acquainted with and this 

 process is repeated until a large number of nuclei have formed in each 

 sporont, which at the commencement of this process rounded off and encysted 

 themselves. Sooner or later, the cuticle surrounding the two encysted parasites 

 dissolves, and the nuclei crowd to the periphery of the united masses of 



1 Laveran et Mesnil, " Sur quel. particul. de I'evot. d'une greg." (C. R. soc. biol., 

 Paris, 1900, lii.. p. 554). 



2 Wolters, M., " Die Conj'ug. u. Sporenbildung bci Greg." (Arch. f. mikr. An., 1891, 

 xxxvii., p. 99). 



3 Math. Ber. aus Ungarn., 1887, iv., p. 146 ; andjourn. R. Micr. Soc., London, 1887, 

 p. 769. 



4 Cuenot, S., " Evolut. d. greg. ccelom. du Grillon dom." _(C. R. Ac. sc., Paris, 1897, 

 cxxv., p. 52) ; " Sur la pret. con-fug, d. Greg." (Bibl. Anai., 1899, p. 70) ; " Rech. sur 

 I'evol. d. Greg." (Arch, de biol., 1901, xvii., p. 581). Siedlecki, M., " Geschl. Vermehr. 

 d. Monoceptis ascidice " (Bull, intern, de I' Ac. d. sc. d. Cracovie, 1899. P- 5 T 5 V Mrazek, A., 

 " Studia o sporozoich " (Vestn. Krai. Ceske spolecnosti nduk, 1899). 



S 



