ON SPERMATOGENESIS IN THE RAT. 
367 
cells of the outer layer from spore cells, which divide in the 
first instance by a process of budding, and the subsequent 
division of one of the resulting cells by karyokinesis, has not 
been confirmed by any previous investigations. It is possible 
that I may have been misled by the appearance of division by 
budding which is occasionally to be seen in these cells in the 
outer layer, and is represented in fig. 7, a ! , consequently I have 
been much interested in finding a similar method of division by 
budding of the nucleus described by Arthur Bolles Lee, in a 
recent 1 paper on spermatogenesis in the Appendicularia. This 
observer suggests a theory to explain the occurrence of the two 
methods of cell division, which is an ingenious one, and cer- 
tainly fits in very well with the account of the process which I 
have given above. 
He suggests that the complex method of division by karyo- 
kinesis is intended to serve for the accurate division of the 
constituents of the nucleus between the resulting cells, so that 
the daughter cells, possessing in an equal degree the properties 
of the parent nucleus, exactly resemble one another. On the 
other hand the method of division by budding consists of an 
elimination of one part of the nucleus from the remainder, so 
that the resulting cells will not exactly resemble one another. 
I have described above the spore cell as dividing by budding, 
and of one of the resulting cells remaining as a spore cell 
while the other divides by karyokinesis, so that the result of 
the division by budding is to produce two dissimilar cells. On 
the other hand, the cell which divides by karyokinesis pro- 
duces the growing cells which are all precisely alike, and these 
later on dividing again by karyokinesis give origin to the 
young spermatozoa which again are all alike. 2 
1 “ Recherches sur l’ovogenese et spermatogenese chez les Appendicularia,” 
par Arthur Bolles Lee, ‘ Recueil Zoologique Suisse,’ vol. i. No. 4. 
2 It might be supposed that the mode of separation of the polar globule 
from the nucleus of the ovum goes against this theory ; but it appears that, 
according to van Beneden, this is not a true process of cell division by karyo- 
kinesis (vide a paper on “ E. van Beneden’s Researches on the Maturation 
and Fecundation of the Ovum,” by J. T. Cunningham, * Quart. Journ. Micr. 
