850 RECORD OF CURRENT RESEARCHES RELATING TO 



author into his accounts of the eye-spots of Stomias and Chcmliodus, 

 which appear to be formed on the same type. 



In Gonostoma, Maurolicus, and Argyropelecus, the structure is 

 altogether different ; they have distinctly the character of glandular 

 organs. Taking for description the first-named of these genera, we 

 find that the form of the organs is oval, and that they consist of a 

 number of radially arranged cones, the tips of which point to a central 

 cavity ; each constituent cone is ordinarily sharply sei>arated from the 

 rest by a thin investment derived from the general investing capsule ; 

 in their more intimate structure they consist of a number of pyriform 

 cells, set concentrically around a central cavity, and there are also 

 two other envelopes, one of which is pigmented, while the other 

 consists of connective tissue ; the pigmented layer is of a dark-brown 

 colour, and resembles generally the pigmented layer found in Chau- 

 liodus ; the characters of this form, as well as the general structure 

 and regular disposition of the parts under discussion, point, in 

 TJssow's opinion, to the common origin of these glands and of the 

 eyes found in the other sets of forms. As before, we must refer our 

 readers to the original for a description of the similar organs in the 

 other genera above mentioned. 



In dealing with the morphology of these organs, the atithor com- 

 mences by pointing out that the arrangements seen in such Inverte- 

 brata as My sis and Pulyophthalmus prevent our associating the special 

 organs of sense with the region of the cerebral ganglia only, and he 

 then insists on the value which the position of the eyes in the Asterida 

 and various Myriapods and Rotatoria has, as comj)ared with the eye- 

 like organs of these fishes ; as may be supposed, therefore, the struc- 

 tures just described are regarded by the Eussian investigator as 

 proper accessory optic organs; as to the gland-like organs of the 

 second series, he points out that no orifice can be observed in them, 

 and he compares them with those special end-organs which are to be 

 found in so many fishes. In conclusion, it is to be noted that the 

 metameric or segmental arrangement of these parts is a point of con- 

 siderable importance. 



Two tables and four plates illustrate the details of the paper. 



Histology of the Cerebellum of Petromyzon fluviatilis.*— The 

 cerebellum of Petromyzon, which, in most of its morphological cha- 

 racters, resembles that of the frog, has been lately subjected to a 

 histological examination by A. Jeleneff. Forming a vertical interpo- 

 sition between the cerebral hemispheres and the medulla oblongata, 

 it is nothing more than a thin plate, and is only separated from the 

 former by a small pit, while the corpora geminata of the frog are not 

 developed in this fish. The necessary process of hardening the cere- 

 bellum was etfected in the following way ; it was first placed for from 

 seven to nine days in a solution of bichromate of potash, and was 

 then exposed for four days to a one or two per cent, solution of 

 chromic acid. After careful washing with distilled water, it was 

 placed in alcohol of 60^ ; the preparations were stained with carmine, 



* ' Bull. Acad. Imp. St. Pe'tersbourg,' xxv. (1879) p. 334, 



