DAVIS: SPERMATOGENESIS. 121 



others, which are also probably paired, although the difference in size 

 is slight. In the gastropods we have the observations of Bonne vie 

 (:05, :06), who found in the oogonia thirty four autosomes, which 

 can be divided according to their size into three groups, each group 

 containing an equal number. She also observed slight variations in 

 the size of the elements within each group. Turning to the vertebrates, 

 we find that similar results have been arrived at by Montgomery 

 (:04) and by A. und K. E. Schreiner (:04, :05, :07). According to 

 Montgomery the spermatogonial autosomes of several salamanders 

 can be grouped in pairs of like volume and form, the components of 

 each pair usually lying close together in the spindle. Similarly the 

 Schreiners have shown that in the spermatogonia of Myxine and 

 Spinax certain autosomes can be recognized by their size, and that 

 in such cases there are always two of equal volume. They also con- 

 firm Montgomery's observations that the components of each pair 

 usually lie close together. 



iNly own results in the Orthoptera are in perfect accord with those 

 of the other observers cited. 



In the light of the results detailed above there would seem to be little 

 room for doubting that in the germ cells of all animals which reproduce 

 sexually, there is a double series of autosomes, one being of paternal 

 the other of maternal origin; but such a series is recognizable only 

 where there are considerable differences in the volumes of the elements. 

 The further fact, first noted by Montgomery (:04), that the components 

 of each jiair are usually closely associated, is significant as indicat- 

 ing a physiological relationship between the two. Montgomery has 

 sought to explain this association on the supposition that during the 

 proj^hases the components of each pair lie close together in a continu- 

 ous linin spireme. This is, of course, based on his assumption (:00) 

 that the chromatin and linin form a single element of w^hich the chro- 

 mosomes are simply subdivisions. It is not my purpose to point out 

 here the many, and as I believe fatal objections to this ^iew, but to 

 consider only its bearing on the association of homologous chromo- 

 somes. If there is any such fixed organization of the nucleus as Mont- 

 gomery imagines, it would seem that the elements of each pair ousrht 

 always to lie close together, but this is certainly not the case. While 

 it is undoubtedly true that such an association is the rule, yet excep- 

 tions are common and the members may be widely separated on the 

 spindle. This is especially well shown in Steiroxys w^here the elements 

 of the largest pair can always be recognized at a glance. In this 

 case the large autosomes usually lie close together, but may be as far 



