Further Studies on Reproduction in Sagitta. 291 



duct, and also on many preparations of the same species contain- 

 ing eggs developing free in the ovary (1905 material). Several 

 preparations of Sagitta bipunctata with eggs in the oviduct were 

 examined with the same result. 



In one egg of Sagitta elegans, containing the second maturation 

 spindle, I did find, near the vegetal pole, a spot of denser cytoplasm 

 (Fig. 36 a and h) which, however, was not at all stained with iron- 

 hsematoxylin. This may have been an early stage of the 'beson- 

 dere Korper,' but could, I think, hardly be a transition stage 

 between the degenerating accessory cell and the 'besondere Kor- 

 per,' since degenerating nuclei nearly always stain dark. 



It also seemed possible that the granules of chromatin-like 

 material extruded from the nucleus in preparation for matura- 

 tion of the egg ('03, PI. 1, Fig. 2 6), a phenomenon which is even 

 more marked in Sagitta elegans (Fig. 37), might have some part in 

 the formation of the 'besondere Korper,' but apparently these 

 granules all disappear completely before this peculiar body becomes 

 visible. At the stage shown in the two figures referred to, small 

 black granules are scattered all through the nucleoplasm and a 

 quantity of larger granules are found outside the membrane 

 between the nucleus and the point of attachment of the egg. If 

 either these granules or the accessory fertilization cell take part 

 in the formation of the 'besondere Korper,' it must be after an 

 intermediate stage in which the material does not stain. 



In a recent paper, Buchner ('10) traces Elpatiewsky's 'besondere 

 Korper' to the degenerate nucleus of my 'accessory' cell, but 

 curiously enough he describes the recently laid eggs as containing 

 "1) das Degenerat der Strangzellen, 2) das Spermium, zwar 

 schon mit einem Strahlenhof umgeben, aber noch nicht zum 

 mannlichen Vorkern aufgequollen, 3) die Telophase der ersten 

 Reifenteilung des Eikerns," and then he refers to his Fig. 5, which 

 is not the stage which he describes but the one where both Elpat- 

 iewsky and I first find the 'besondere Korper.' (Compare Buch- 

 ner Fig. 5, Elpatiewsky Fig. 3, Stevens Figs. 24, 28, 29). 



The ''mit Eisenhsematoxylin sich tief schwarzendes Netz" to 

 which Buchner refers and upon the importance of which he lays 

 considerable stress in connection with his hypothesis of the chromi- 



