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On the Ovogenesis and Spermatogenesis of Sagitta 
bipunctata. 
By 
N. M. Stevens. 
(Aus dem Zoologischen Institut der Universitat Würzburg.) 
With plates 20 and 21. 
This study was suggested to me by Prof. Tu. Boveri, to whom 
I am deeply indebted for permission to work in his laboratory, during 
the summer semester of 1902, and for helpful suggestions and criticism. 
An investigation of the ovogenesis of Sagitta was undertaken: 
1) in order to determine what light it might throw on the Reduction 
Question; 2) to ascertain the relation between the large chromosomes 
of the germ nucleus and the very small ones in the maturation spindles, 
as seen by Bovzrı (1890). No satisfactory results were obtained on 
the first point, but to the second question a definite answer can be 
given. 
As the preparations included sections of the testis, a study of 
the spermatogenesis of Sagitta was also made. The material is 
particularly favorable, as all stages in the development of both ova 
and spermatozoa may be found in the same individual. 
Method. The animals were preserved whole, and cross-sections 
cut through the region containing the ovaries and testes. As fixing 
agents, HERMANN’s platinum chloride-osmic-acetic mixture, FLEMMING’s 
strong chrom-osmic-acetic solution, BovERt’s picro-acetic, 70 °/, alcohol, 
and sublimate acetic were used; but only the latter — concentrated 
sublimate solution with 2—5°/, glacial acetic — gave satisfactory 
results. | 
A part of the material was stained in bulk in borax carmine and 
in DELAFIELD’s haematoxylin; but by far the best results were ob- 
tained from sections 5—7 u thick, stained on the slide by HEIDEN- 
