Miscellaneous. 305 



ascribes to them ia the adult Sacculinu. The ovules, in the larva, 

 at least during the first period which follows the exclusion of the 

 latter, evidently only represent simple cells with their ordinary con- 

 stituent parts — namely, a protoplasm which is sometimes homo- 

 geneous, sometimes more or less granular, according to the state of 

 development, and a nucleus or germinal vesicle, 0-014 miUim. in 

 breadth in the most advanced ovides, and furnished with a single 

 nucleolus or germinal spot, which is comparatively large and well 

 marked. Moreover by means of reagents we may display an 

 enveloping membrane surrounding the ovules ; but this appears to 

 me to be rather a capsular envelope than a real \dteUine membrane. 

 AVTiat are the modifications undergone by the reproductive appa- 

 ratus during the successive phases through which the larva passes 

 before commencing its sedentary and parasitic existence ? My in- 

 vestigations have taught me nothing about this ; for I have not been 

 able to meet with the larva again until, fixed upon the abdomen of 

 the Pagurus, it had become transformed into the adult animal, a 

 sort of pouch filled with eggs, in which the latter pass through all 

 the stages of their ovarian and embryonal evolution. At this period 

 of their life the ovarian rachis of the larva has become transformed 

 into a ramose organ, the numerous divisions of which serve to sup- 

 port a multitude of ovigerous follicles, which are appended to it as 

 the grapes of a bvmch are to its ramifications. When the ovary is 

 torn under water, the elements enclosed in the ovigerous follicles are 

 set free. These are, in the first place, some spherical bodies ren- 

 dered opaque by the numerous refractive globules contained in their 

 interior ; these are easily recognized as ova more or less approaching 

 their period of maturation. Their diameter varies between 0-13 

 and 0-15 millim. We shidl revert hereafter to the constitution of 

 these bodies. Side by side with them we see a great number of 

 other smaller elements, as to the signification of which we may at 

 first hesitate. Some of them are regularly round cells, 0"02-0-03 

 millim. in breadth, formed of a transparent, finely granular proto- 

 plasm, with a nucleus 0-015 millim. in diameter, furnished with 

 a simple, large and rounded, very refractive nucleolus. The others 

 have a bilobed form, and appear, at the first glance, to be constituted 

 by the adhesion of two of the preceding cells ; but a more careful 

 examination soon shows that they are merely a state of division of 

 the latter. 



Thus we see all the forms intermediate between the simple cells 

 and the bilobed bodies, namely : — cells still regularly spherical, but 

 already enclosing two juxtaposed nuclei ; others which begin to 

 exhibit a median constriction of their body, with a tendency on the 

 part of the two nuclei to separate from each other ; others, finally, 

 in which the two new cells are already well defined, but remain 

 adherent by a larger or smaller part of their surface. 



In these last elements we readily recognize the bilobed ovules of 

 M. Gerbe, or the mother cells in their difierent states of division 

 described by M. van Beneden. I have but little to add to the de- 

 scription given of them by this latter observer. The two daughter 



Ann. & Mag. X. Hist. Ser.4. Vol. v. 21 



