The spermatogenesis of Paripatus (Peripatopsis) balfouri. 343 



This cell seems to contain 34 chromosomes, i. e. 6 more than the 

 number in the spermatogonia ; but probably in some cases portions 

 of the same chromosome may have been contained in each section, 

 so that it is probable that only 28 chromosomes are present. 



One egg cell was found in the prophase of the 1st maturation 

 division. Unfortunately this large cell extended over several sections 

 and some of the sections had been lost so that the number of chromo- 

 somes could not be determined. This cell was supported by a stalk 

 to the outer wall of the ovary, and was not free in the uterus. 



4. Embryonic Cells. 



In one of the oviducts at my disposal was a young embryo with 

 numerous mitoses. 



Fig. 229, Plate 23, represents a monaster stage of one of the 

 large entoderm cells, showing all the chromosomes, of which there 

 seem to be exactly 28. 



Fig. 202, of the same Plate, represents a lateral view of a stage 

 ill the formation of the monaster from an ectoderm cell of the same 

 embryo: only a few of the chromosomes shown. This figure shows 

 an appearance of the centrosomes which was not seen by me in any 

 cells of the spermatogenetic series, namely the centrosomes are either 

 very large or else there is an attraction sphere around each of them. 

 Numerous cases of ectodermic mitoses were found, and in them the 

 number of chromosomes seemed to be approximately 28. 



These observations render it probable that in the tissue cells 

 examined, in the ovogonia, and in the embryonic cells the number of 

 the chromosomes is 28. It is also interesting to note that in all these 

 cells the form of the chromosomes is like that of those of the spermato- 

 gonia. 



IX. General Part. 



Here I do not intend to give any general summary of my observ- 

 ations, but only to present a few general conclusions in regard to 

 a certain portion of the observations. 



1. Relations of Chromatin andLlnin; tlie Chromosome Concept; 

 the Individnality of Chromosomes. 



Within the nucleus, besides the nuclear sap (caryolympli) and the 

 true nucleoli, are found the structures which compose in the resting 



