82 QUARTERLY CHRONICLE OF MICROSCOPICAL SCIEXCE. 



The nerves employed are the long and slender thoracic nerves 

 of the mouse. They are dipped in a solution of nitrate of 

 silver (1 to 300), then washed in distilled water and examined 

 in glycerine. The entire nerve, under a magnifying power of 

 150 diameters^ shows very clear small transverse bars, which 

 are cut at a number of points by another small vertical bar, 

 so as to represent a number of Latin crosses. It may then 

 be seen that the transverse limb of the cross corresponds to 

 the axis-cylinder. If the nervous thread be dissected and 

 treated with a neutral solution of picrocarminate of ammonia 

 (1 in 100), the matter becomes very clear, and it is easy to 

 make out that each little cross corresponds to ?i strangulation, 

 near which the axis-cylinder appears of a faint yellow colour. 

 It then becomes more and more distinct with the carmine 

 coloration, expands, and becomes covered with drops of 

 myeline, which is hardly or not at all coloured. With a 

 power of 800 diameters the strangulation in question is seen 

 to be caused by a true discoid ring, which acts there as a 

 collar constricting the nerve-tube. In dissected preparations 

 the rings as well as the axis-cylinder are coloured black by 

 solution of nitrate of silver at the level of the strangulation. 

 It hence follows that both the picrocarminate and the silver 

 solution pass through the ring and reach the axile centre 

 of the nervous cord. The conclusion is, in fact, that liquids 

 can penetrate into the nerves, and that the curious arrange- 

 ment observed by M. Ranvier constitutes the place where 

 and, in a certain sense, the organ by which this penetration 

 takes place. 



Ranvier has been led to conclude that the nervous cord 

 is enclosed in a true serous cavity with an epithelial lining. 



[As previously stated by Strieker and others : see Dr. 

 Klein^s article in this number of the Journal, p. 21. — Ed.] — 

 Revne Scientifique. 



VIII. Organs of Sense. — 1 . Morano on the pigment layers of 

 the retina (' Schultze's Archiv' viii, 81). 



2. Reichert (' Reichert und Dubois Reymond's Archiv,' 

 1871) has completed his memoir on the labyrinth of the ear. 

 (" Gehorschnecke.^^) 



3. Dobrowolski ('Schultze's Archiv,' viii) describes "double 

 cones" from tlie retina. 



4. In another paper on the retina he discusses the ellipsoid 

 or lenticular bodies of Krause and Schultze. 



5. Schmid on the lymphatic follicles of the eye ('Die 

 LymphfoUikel der Bindehaut des Auges.' Wien, 1871.) An 

 exhaustive study of these structures, beautifully illustrated. 



IX. Vascular System — The development of vessels in in- 



