DEVELOPMENT OE DISTIOHOPOEA VIOLACEA. 67 



Gregarines which form during encystment a vast number of 

 spores, no karyokinetic figures can be observed. 



Many years ago Hertwig (24) described a curious method of 

 the fragmentation of the nucleus without karyokinesis in the 

 spore formation of Thalassicola, and more recently Brandt (4) 

 was unable to find karyokinesis in the divisions of the nucleus 

 to form the nuclei of the spores of the Sphserozooids. 



Gruher (16) has described several instances among the 

 ciliate Infusoria in which the nucleus apparently fragments 

 into extremely minute granules, which become scattered 

 through the protoplasm of the body and collect again into 

 lumps. 



Jickeli (29) has described fragmentation of the nucleus of 

 Stylonychia, Paramoecium, and other Giliata. 



Quite recently, too. Lister (39), in his researches upon 

 Orbitolites, has not been able to discover any signs of karyo- 

 kinesis in the division of the nuclei. 



There is probably, too, a method of fragmentation in the 

 spermatogenesis of many animals. I have myself carefully 

 examined the earliest divisions of the nucleus of the sperm 

 mother-cell of Millepora, Allopora, Distichopora, and Alcy- 

 onium, and I can find no trace of karyokinesis. It is, in fact, 

 only in a few exceptional cases, such as Ascaris (Hertwig, 25), 

 where the cell outlines of the spermatocytes are very early 

 delineated, that karyokinesis has been observed in the division 

 of the nuclei of the sperm mother-cells. 



Verson (56) shows that in Bombyx mori the primordial cells 

 have at first a giant nucleus, which divides amitotically to form 

 numerous secondary nuclei, and these divide mitotically to 

 form the nuclei of the Spermatids. 



BoUes Lee (38) found amitotic division of the nuclei of the 

 spermatogonia of Ch^tognatha and Nemertines and regular 

 karyokinesis in the division of the nuclei of the spermatocytes. 

 Dostojewski found the same thing in the spermatogenesis 

 of Amphibia (see Waldeyer, 58, p. 39), and other examples 

 could be quoted from the writings of La Valette St. George, 

 Gilson, Sabatier, and others (see Waldeyer, 58, p. 39). 



