I 



HUMAN SPERMATOGENESIS: A STUDY OF INHERITANCE. 5 



of these plasmosomes would seem to be those granules frequently found near the 

 spindle poles during division (figs. 15-17, 19-23). Distinct from these are two 

 dense bodies, or different volumes, the allosomes or modified chromosomes, which 

 always lie against the nuclear membrane. The name " allosomes" to denote 

 modified chromosomes was introduced by me in an earlier paper (190G). 

 Sometimes the two are separated (D, d, figs. 3, 6) ; sometimes in close contact 

 (figs. 2, 4, 5). Only by the Ehrlich-Biondi triple stain, used after Bouin'e fixa- 

 tion, can the plasmosomes be sharply distinguished from the allosomes; the 

 former then stain red (acidophilic), the latter, like the chromosomes, green 

 (basophilic). The later history will make it clear that the basophilic bodies are 

 true allosomes and not chromatoid nucleoli. These are probably allosomes of 

 the kind called by Wilson idiochromosomes, for they appear to become first 

 differentiated in the spermatocytes. The larger of the allosomes we will call D, 

 and the smaller d. 



Late prophases (diakinesis) of the first maturation mitosis are shown in 

 figs. 7-12, of which the last four exhibit all the chromosomes. In figs. 10 and 

 11 exactly 12 chromosomes can be seen; this is also the case in figs. 9 and 12, 

 provided the bodies marked x is each a geminus. Ten of these 12 must be gemini 

 or bivalent chromosomes judging by their later history and by analogy with other 

 species; they exhibit great form diversity, the elements of a geminus being con- 

 nected terminally or laterally, or irregularly bent around each other. Until their 

 method of formation is known it would be useless to speculate as to their exact 

 constitution, and as to whether it is in the first or second maturation mitosis 

 that they divide reductionally. The two remaining elements are the univalent 

 allosomes, but in these late prophases it is practically impossible to say which 

 two these are. 



In the first maturation mitosis several variations may be distinguished, 

 with regard to the behavior of the two allosomes, as follows: 



Condition A, both allosomes lying at the same spindle pole, found in 59 

 cases. This is shown in figs. 13-17. The polar view, fig. 13, shows 10 ordinary 

 chromosomes (autosomes), and at a different level from these the two allosomes 

 (D, d), while figs. 14-17 show the same condition on lateral view; fig. 14 shows 

 all the chromosomes. 1 



Quite frequently each of the allosomes shows a longitudinal split (figs. 14, 

 17). In this condition A both allosomes must pass undivided into one of the 

 secondary spermatocytes. 



Condition B, allosome D lying at one pole, allosome d at the opposite pole, 

 found in 5 cases (Fig. 18). As a result of this one secondary spermatocyte 

 should receive D, and the other d. 



Condition C, allosome D at one pole, while d has divided and one of its pro- 

 ducts lies at one spindle pole (figs. 19-22). This was found in 10 cases. In figs. 

 19 and 21 all the chromosomes are drawn. As a result of a division of any such 



1 In all figures only those chromosomes are drawn that can be seen distinctly, the others are omitted. 





