48 H. M. WOODCOCK. 



part of /;; from this to tZ is a slight transition. In all these 

 cases there is no longer any sign of kinetic apparatus and 

 the nuclear membrane has also quite vanished. A portion of 

 the cytoplasm around each has been drawn as well, and^ while 

 in b and c the delimitation of the nuclear material is still fairly 

 well marked, in d there is no distinct boundai-y between the 

 two constituents, the gi'anules at the periphery spreading out 

 into the cytoplasm.^ 



This separation of the nuclei into two kinds represents the 

 only nuclear purification, or elimination of unnecessary chro- 

 matic material, which occurs in Cystobia irregularis. 

 The germinal nuclei, after one or two more divisions, become 

 the nuclei of the primary sporoblasts, the formation of which 

 we have now to consider. 



(8) FoKMATiON OP Gametes (Sporoblasts) and Conjugation. 



Fig. 56 is a section through a cyst of C. irregularis in 

 which the spoi'oblast nuclei (n) are all formed. The nuclei 

 have now a certain definite arrangement, being situated at 

 or near the periphery of irregularly shaped lobes or portions 

 of the cytoplasm, which, indeed, they mark out and delimit. 

 In other words, we find in Cystobia the same intertwining 

 and interlocking of the two cytoplasms (one belonging to 

 each half or member of the '^couple '^) that Siedlecki describes 

 for Lankcsteria, and Cueuot for Monocystis. In Cys- 

 tobia, however, especially in C. rainchinii, the process 

 is carried to a much greater extent, which is easily to be 

 understood when the far more intimate nature of association 

 in this genus is remembered. 



Seen in section," this mutual interlobing is here of such a 



• Tlie general cytoplasm up till now has been entirely I'lee from cliroma- 

 toid or nuclear matter, not staining witli iron liaematoxyliu; in later stages, 

 however, this is no longer the case, chromatoid granules being very much in 

 evidence and persisting more or less conspicuously throughout sporoblast- and 

 spore-formation. 



* Uiifortuiialely, nothing whatever is visible in an advanced cyst stained and 

 mjunled whole until the dulinitive s[)oroblaits (zygotes) or s|)ores are formed. 



