No. 3-] MORPHOLOGY OF THE STEXTORS. 531 



regarding as superfluous micronuclei undergoing digestion. 

 The vesicle may be compared to a digestive vacuole. 



In the later stages of conjugation, the separated nodes of the 

 old meganucleus stain less deeply, and begin to lose their 

 spherical contour. The example represented in Fig. 60 is from 

 an ex-conjugate, being from the same specimen as Fig. 57. 

 The chromatic reticulum is still existent. At two points clear 

 vesicles, probably of karyoplasm, cause the nuclear membrane 

 to bulge out. I have never seen such vesicles in the ordinary 

 state of the meganucleus of Stentor. 



E. Teratology. 



As Balbiani has remarked in a recent paper ('9l), the tera- 

 tology of Protozoa is an almost untouched field of investigation, 

 and is certainly a promising one. Balbiani' s own contribution 

 ('91) to the subject is based upon the study of two double 

 monsters of S. cceruleiis, one of them artificially produced by 

 merotomy. In a still more recent and very suggestive paper 

 {'92), the eminent French micrograph er has shown how double 

 monsters of Stentor may be produced at will by the merotomy 

 of specimens in the earlier stages of fission. My own results 

 are also derived from the study of a double monster of 5. 

 ccendeiis, one which was not produced artificially. 



When discovered, the specimen presented nearly the appear- 

 ance shown in Fig. 61 A, with the exception that the anlagen 

 of new zones (a.z.,'^ a.z.i) had not appeared. The animal has 

 the aspect of being in a stage of fission soon after the appear- 

 ance of the constriction. The new adoral zone (a.s^) had, 

 however, no mouth at its lower extremity, although the place 

 for it was marked by a deep fold, into which the posterior 

 extremity of the new zone penetrated. Another peculiarity is 

 the reversed position of the anterior zooid. The twist is plainly 

 indicated in the direction taken by the stripes, which apparently 

 present a distinct system for each zooid, meeting each other 

 at a wide angle in the fission-line. As the ramifying zone ^ 

 of the anterior zooid is placed far to the right of its normal 

 position, it is evident that the torsion has been from left to 



1 Its position is indicated by the new adoral zone a.z^. 



