548 



phase and not by the direct transmigration of unsplit chromosomes 

 to the poles, as the then previous publications would have led one to 

 suppose. For at that time all the many results of 0. Hertwig's splendid 

 work on the spermatogenesis of A scar is 1 ) remained unchallenged, 

 and quite a host of similar descriptions had spread out from it, as 

 from a nucleus, on all sides. Dr. Ischikawa in his spermato- and 

 ovi-genesis of Diaptomus, enthusiastically confirmed Hertwig's 

 description of the reduction process, and even remarked that it was 

 hardly necessary to publish further details of a process already seen 

 in some cases to occur, and which, according to the Weismannistic 

 conceptions of heredity, was theoretically a necessity. 



In 1893, however, Brauer dealing' 2 ) with the self-same question, 

 and again in Ascaris, arrived at exactly opposite results. 



A clear conception of reduction among physical entities which, to 

 say the least, must stand as "Godfathers" to the hereditary struc- 

 tures they determine, was by no means easy to grasp, long before 

 Brauer had contributed to the subject or that I myself had found the 

 mitoses of Mammalia were absolutely normal ; and these difficulties seem 

 to have been equally present to others, for the whole complex and 

 even quasi- metaphysical subject was discussed by Boveri in a cri- 

 tique 3 ), as able as it was at the time necessary, concluding with 

 the pregnant phrase: "Durch die vorstehenden Erörterungen glaube 

 ich gezeigt zu haben, daß zwar gewisse Vorgänge beschrieben worden 

 sind, die vielleicht mit der Chromosomenreduction im Zusammenhang 

 stehen, daß uns aber eine wirkliche Einsicht in diesen Vorgang bis 

 jetzt fehlt. Es bleibt weiterer Forschung vorbehalten, dieses Dunkel 

 aufzuklären." 



The so-called reduction phenomena of the cartilaginous fish which 

 I have examined, would fit in admirably with the half theoretical 

 anticipation of Boveri in the above cited article, as well as with what 

 actually takes place in Mammals, and what Brauer regards as the 

 more correct rendering of the same phenomena in Ascaris. 



The young reproductive organs of the future male Scy Ilium 

 are conspicuously hermaphroditic, although I cannot find any reference 

 to this fact in the literature with which I am acquainted; nor was 

 Prof. Mayer, whom I consulted on the subject, aware of any reference 

 regarding it. This probably arises from the fact that as the testes 

 grow older the hermaphroditic character dies out. 



1) Arch. f. mikr. Anat, Bd. 36, p. 1. 



2) Ibid., Bd. 42, p. 153. 



3) Ergebnisse der Anat. und Entwickelungsgeschichte, Bd. 1, 1891, 

 p. 466—467. 



