ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 557 



Previous observers have noted the occurrence of conspicuous 

 structures upon the antenufe of Chilognatha, which correspond to the 

 so-called olfactory cylinders of insects recently studied in detail by 

 Hauser,* and between the two there seems to be a general similarity. 



Each of the sensory processes is entered by a nerve which imme- 

 diately divides into two branches, each covered with ganglionic cells 

 which are distributed in two groups, the anterior one consisting of 

 considerably smaller cells than the posterior ones ; at the distal 

 extremity the nerve-fibres again collect into a bundle and form the 

 termination of the organ ; that these fibres are differently constituted 

 from those which enter the ganglion below is shown by the fact that 

 their behaviour to staining reagents is different ; the sensory process 

 is often at the free extremity so that a direct communication is 

 established between these nerve-endings and the outer world. 



A structure essentially similar to this is found in Vespa, but is 

 differently construed by Hauser; according to him the posterior 

 group of cells is not present since he only figures one nucleus, with 

 several nucleoli however, while the anterior group of smaller cells has 

 escaped his attention ; accordingly the conclusion to which Hauser 

 has arrived at is that the whole sensory structure is a single cell ; 

 whereas in reality it consists of a great number of cells. 



Ovum of Geophili.f — E. G. Balbiani records some observations 

 made on the development of the germinal vesicle and the follicular 

 cells of the ovum in Geophilus. In the fresh ovum the germinal vesicle 

 is spherical; when treated with dilute acetic acid a funnel-shaped 

 hollow process is seen to arise from the germinal vesicle ; one end of 

 this is in close connection with the germinal spot and a process of the 

 latter can be observed to penetrate the cavity of the funnel. It is 

 covered externally by a delicate layer of vitelline protoplasm. In 

 adult females this " nuclear appendix " has the form of a long coiled 

 thread, sometimes it is represented by a number of variously sized 

 cylindrical masses, at other times by several round bodies scattered 

 through the substance of the vitellus ; the latter conditions are 

 evidently the result of a division of the coiled thread-like nuclear 

 appendix, but the division is never complete inasmuch as a considerable 

 portion always remains adherent to the germinal vesicle. Each of 

 these small round bodies into which the nuclear appendix splits up 

 contains all the elements which go to form the ovum, viz. a portion of 

 the germinal vesicle, the germinal spot, and the vitelline protoplasm. 

 The wall of the follicle which incloses the ova is seen to contain a 

 number of small cells which agree in every respect with these small 

 cellular bodies resulting from the division of the nuclear appendix, 

 and the view that they originate from the latter is confirmed by the 

 recent investigations of MM. Fol, Eoule, and Sabatier on the ovum of 

 Ascidians. The follicular cells appear therefore to be the homologues 

 of the spermatoblasts in the male, and the " vitelline nucleus " also 

 corresponds to one of the same. 



♦ Zt-itschr. f. \Vis8. Zool, xxxiv. (1880) p. 367. 



t Zool. Auzeig., vi. (1883) pp. G58-G2 (7 figs.), G76-80 (3 liga.). 



