Notes oil a New Boveria species. 15 



III. Fissions following the conjugation. 



The most prominent cytological changes accompanying the 

 first fission of tlie ex-conjiigant are presented by both its micro- 

 nucleus and meganucleus. The process of the first micronuclear 

 division is entirely similar to that described by Stevens in the 

 Neapolitan form of Bovei-ia. The chromatin mass first contracts 

 into a crescont-hko shape and subsequently divides, by two 

 cleavage planes crossing each other at right angles, into four com- 

 paratively thick chromosomes which later are so disposed as to be 

 parnhel to one another. Then the entire micronucleus is trans- 

 formed into a long spindle, the four chromosomes taking the 

 equatorial position as usual. The subsequent processes are on the 

 whole similar to those before described in the divisions of the 

 synkarion. The two daughter micronuclei (fig. 15, n) on entering 

 the resting stage, separate from each other and place themselves 

 one at each end of the now elongated meganucleus. The mega- 

 ^. ,_, nucleus elong-ates more and more in the 



Fig. IS. = 



direction of the body-axis ; meanwhile, 



t^^^^ i^^ granular contents contract and divide 



^'"-^jV's, ,-•' into three nearly equal-sized masses, lying 



'y.ci.si --i^r'iîiy— ' f-^-^]f^ one behind the other. In the two clear 



/y-.-^ « ' spaces between the middle and the other 



'^ -f'^^^j two masses, there are found in all three 



. •-.'•*••' . chromatin granules (fig. 15, rj. d. syi^-^), 



^/" which are conspicuously larger than 



any of the darkly staining chromatin 

 ^. ,r -,- w X ., ^ -. granules in each of the three mega- 



Figiu-e 15— 1( relate to the first ° ° 



binary fission after the conjugation, nuclear grauular masscs. Tlicy vary 



Iron-hœmatoxylin. All the reference 



letters are the same as those in the SOmewliat iu sliapC, but are ill lUOSt 



precsc ng gures. cascs cresccutic. As poiutcd out before, 



