INVEKTEBRATA, CRYPTOGAMIA, MICROSCOPY, ETC. 271 



one another till they form a small number of largish sarcode-bodies. 

 When these granules have thus fused to some extent, the germinal 

 vesicle begins to shrink as the yolk drives it towards the periphery 

 of the egg ; on reaching this it forms the first directive corj^uscle, 

 below which and evidently derived from the same vesicle there is an 

 irregular clear space, in which the remains of the germ-spot may be 

 made out ; this represents the second directive corpuscle. But now, 

 below these, there is an irregular and still smaller clear space ; this is 

 formed by the remains of the germinal vesicle, and in it there are a 

 few very pale and delicate corpuscles, which would likewise seem to 

 be derived from the germinal spot. The clear area now contracts 

 and withdraws itself from the periphery ; soon a clear round spot 

 appears in its place, and around this the substance of the yolk is 

 radially disposed. The rays elongate, and two pale bodies, altogether 

 similar to those which remained when the germinal spot was broken 

 up, appear in the central portion. Shortly there appears a second 

 radial figure, which is only distinguished by having a clearer centre 

 and only one nuclear body. These two figures approach one another 

 slowly, touch, and finally completely fuse. The two or three nuclear 

 bodies of the first star first unite with one another, and then fuse 

 with that of the smaller figure. All this calls strongly to mind the 

 fusion of the sperm-nucleus with the ovarian nucleus which has been 

 observed by Hertwig, Fol, &c. ; but the author directs attention to 

 the fact that the whole process described by him in this paper may 

 take place in an unimpregnated ovum. 



Greef has already observed that in A. ruhens the mesodermal cells 

 begin to be developed from the ectoderm previously to the first in- 

 vagination, and previously, therefore, to the formation ot the endoderm. 

 He has now repeated that observation, and finds that the cells of the 

 mesoderm may not only be developed at the point of the ectoderm at 

 which the invagination afterwards commences, but that they may 

 appear at any point on the ectoderm. The mesoderm is the scat of 

 origin of the whole of the calcareous skeleton. 



Ccelenterata, 



Tactile Organs of Eucharis multicornis.* — Eimer gives an 

 account of these organs in the above-mentioned Ctenopliore, where 

 the distal end of tho tactile processes are beset with specially modified 

 cells. These cells are rounded in form and are filled with grauular 

 contents ; they are grouped in racemose fashion, and cover over tho 

 rounded end of the " tactile wart " ; tho most anterior or distal aro 

 some ton times larger tlian tlie outer or more proximally placed 

 cells ; their envelope is delicate. Between these bodies there project 

 tufts of three or four distnlly diverging, apparently homogeneous 



SOtSB, 



Tho gelatinous tissue composing the warts is traversed botli 

 longitudinally and transversely by numerous fibres, which appear to 

 be nervous in character ; tliey have not only a close rcsomblauce to 

 the nerves which, as tho author has described, supply the epidermis 



♦ ' Arch. Mikr. Anut.,' xvii. (1879) p. 342. 



