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A Neiv Gregarme 
take place in vivo, probably owing to the rapidity of the process, and I 
have failed to find indications of conjugation in stained preparations. 
Only sporonts and completed cysts could be detected. In one cyst, 
however (Fig. 17), there is slight evidence that the sporonts join tail to 
tail for the cap-like thickening of the ectoplasm in the protomerite of 
the sporont is seen in this cyst at opposite poles. The changes of 
structure which it undergoes after conjugation seem to proceed equally 
well whether the cyst is in the gut or in the excreta, yet as the earlier 
changes are usually seen in the gut and the later ones in the excreta 
we arbitrarily describe the following changes as exclusively occurring in 
these situations. 
Fig. 12. Fig. 13. 
Fig. 12. Nucleus of sporont. 
Fig. 13. Chromatin band of the sporont assuming different forms. 
Fig. 14. Types of nuclei of the sporont later than in Fig. 12. 
Fig. 15. Polar bodies containing others. 
In the gut the cyst consists of a roughly spherical body about 85 g in 
diameter when uncompressed. At first it is composed of two halves 
(Fig. 18) enclosed in a common ectoplasm derived from the engaged 
sporonts. The endoplasm is densely granular. Sometimes, especially 
just after association has taken place, the nucleus of each hemisphere 
can be seen as a clear vesicular area in the midst of the endoplasm 
(Figs. 16, 19), but more often nothing can be made out (Figs. 16, 18). 
At any rate nuclear changes proceed rapidly, and the cyst wall 
meanwhile becomes thicker. The partition of ectoplasm between the 
two halves of the cyst is finally lost, and this now consists of a 
