sooLoar and botany, microscopy, etc. 37 



was not determined. His description of the rest of the nervous system 

 does not reveal any fact of special importance. 



(4) Sense-orgayis* — The median eye and the frontal organ are strictly 

 inseparable structures. The structure and movements of the former 

 are briefly described. The structure and nervous relations of the latter 

 clearly point to a sensory function. Its connection with the eye is 

 described. 



(5) Reproductive Organs, (a) The Male. — The testes are spherical 

 and lateral in position, slightly in front of the rectum. The epithelial 

 cells giving origin to spermatozoa, and the rigid form of the latter are 

 described. The vasa deferentia with delicate elastic walls, with an 

 anterior epithelium like that of the testes, w r ith a posterior epithelium 

 near their union, apparently glandular, are then described. They unite 

 to form the penis, which has a funnel-like form, and a strong sheath of 

 circular muscles. The w urethra " has a superior section like an X, but 

 further down becomes triangular. A small sac-like reservoir is formed 

 superiorly, and lined with cylindrical epithelium. The walls of the 

 penis are in part glandular. A pair of thoracic appendages are intimately 

 associated with the penis, which opens at their free extremity. They 

 end in two chelate structures, which have an accessory glandular 

 apparatus, and are intimately described. 



(6) The Female. — The internal arrangements have been already 

 described by Claus. The external sexual appendages end in two large 

 ovoid glands, which contain small refractive spheres, mixed with 

 numerous needle-like crystals. Bichloride of mercury in aqueous solu- 

 tion, in which the organisms were left for 5-7 minutes, followed by 75 

 per cent, alcohol, and Mayer's fluid (Kleinenberg's plus nitric acid) 

 yielded the best results. 



Vermes, 

 a. Annelida. 



Germ -layers of Clepsine.* — Prof. C. O. Whitman deals very 

 thoroughly with the history of the germ-layers in Clepsine and its allies. 

 He commences with an account of the process of cleavage, in which 

 bilateral symmetry early becomes established. In dealing with the 

 history of the mesenteron he points out that the earlier endoderm cells 

 arise beneath the cephalic lobe, and are probably budded off from the 

 endoblasts as distinct cells ; to these, others are soon added, which first 

 arise as endoplasts, so that no line of distinction based on the mode of 

 origin can be drawn. The larger portion of the mesenteron, or all but a 

 small oesophageal portion, passes through several stages of development ; 

 the first is represented by three large macromeres or endoblasts, the 

 second by endoplasts (each a nucleated mass of protoplasm without cell- 

 boundary) ; the third by an exceedingly thin layer of flattened epithelium, 

 and the fourth by a columnar epithelium. 



Fresh arguments and evidence are brought to prove that the entire 

 ventral nerve-chain arises as two simple longitudinal rows of cells, and 

 that each row is produced by the continued proliferation of a single cell 

 — the neuroblast. Connected with the neural cell-row is another which 

 the author calls the nephric, and evidence is afforded that the nephridia 

 are derived from the ectoderm, that they make their earliest appearance 



* Journ. of Morphology, i. (1887) pp. 105-82 (3 pis.). 



