Dr. C. Chun on the Siphonophora. 157 



demonstrated in different Eudoxice that this second nectocalyx 

 represents an accessory structure, destined in course of time to 

 replace the first large one, I have detected the first rudiment 

 of this second calyx in the form of a small bud (fig. 2, x) even 

 in the groups still adhering to the stem of the Muggicea. It 

 seemed to me of interest to obtain an answer to the question 

 whether a regular succession of new genital nectocalyces takes 

 place, and also whether during this change the sex of the 



Eudoxice is altered. Without describing the precautions by 

 means of which I succeeded by suitable aeratiou and nourish- 

 ment in keeping the delicate colonies alive for some days, I 

 may state that, besides the above second accessory bud, the 

 foundation of a third, and, as I succeeded in ascertaining 

 in one case, also that of a fourth bud became developed. As 

 soon as the oldest calyx has emptied out its genital pro- 

 ducts, which usually takes place while it is still connected 

 with the Endow ia, it is displaced and pushed off by the 

 rapidly growing reserve calyx, which then in its turn under- 

 goes the same fate. But the reserve calyces always produce 

 the same sexual products as the first calyx ; no change of sex 

 therefore takes place. As I have been able to confirm 

 Leuekart's statements with regard to the change of the re- 

 placement-nectocalyces in Eudoxia campanula, and as further 

 similar replacement-buds have been observed in all carefully 

 investigated Diplophysce and Eudoxice, we may assert generally 

 that the Eudoxire, without alteration of sex, successive!// pro- 

 duce a brood of medusiform sexual animals by a process analo- 

 gous to stabilization. 



If we examine the genital manubrium when filled witl 

 mature ova, we observe in them a peculiar phenomenon. 

 They lie between the ectoderm and endoder.n, of which the 

 latter almost entirely clothes them, leaving free only a small 

 part of the surface which is in contact with the ectoderm. At 

 this spot we always find the large peripherally placed nucleus, 

 with its nucleolus. Between the ectoderm and the part of 

 the periphery of the ovum which is not covered by the endo- 

 derm, some fluid collects, in which from two to three direction- 

 vesicles are to be detected. Muller, who first called attention 

 to this peculiarity, regarded this arrangement as a micro pylar 

 apparatus. I cannot, however, agree with him in this view, 

 as I could neither find an aperture in the ectodermal lamella, 

 which is sometimes dilated and thin, nor meet with fecundated 

 ova in the genital manubrium. What Muller regards as 

 spermatozoa that have penetrated are evidently only the 

 direction-vesicles. The nucleus, with the surrounding plasma, 

 is usually overflowed by the neighbouring ectoplasm, so that 



i 



