QUARTERLY CHRONICLE OF MICROSCOPICAL 



SCIENCE. 



Siebold and KoUiker's Zeitschrift. f. wissensch Zoologie. — 

 Bd. xviii, heft i. 



I. Studies on the Central Nervous System in the Osseous 

 Fishes, by Dr. Ludwig Stieda. 



In 1861j Dr. Stieda published, under the title of 'The 

 Spinal Chord and some part of the Brain of Esox Lucius,^ 

 certain observations on the central nervous system of the 

 pike. Since then he has investigated the same parts in 

 various classes of the vertebrata, and the results so far as con- 

 cerns the osseous fishes, are given in the present valuable com- 

 munication, illustrated by two plates. The subject is treated 

 under the heads of (1) the nerve-cells; (2) nerve-fibres j 

 (3) the connective tissue and blood-vessels; and (4) the 

 epithelia. 



The cells, both peripheral and central, are described as 

 bodies furnished with a vesicular spherical nucleus, and 

 usually also with a nucleolus. They have no cell-membrane, 

 and are consequently to be regarded as simple masses of 

 protoplasm, which presents a finely granular aspect. These 

 cells differ in size and form, the latter depending upon the 

 number of processes given off, and which vary in number 

 from one to four or five. The processes are merely continua- 

 tions of the granular cell-substance, and, so far as the author 

 has seen, are never connected with the nucleus. He regards 

 the apparently apolar cells as artificial products, and he has 

 never noticed any division of the processes, nor any connection 

 between one cell and another. Besides these true nerve- 

 cells, the central nervous substance presents numerous 

 minute cellular elements, whose nature is not quite deter- 

 mined, but which have been termed "granules" from their 

 resemblance to the so-termed "granules" in the retina. 

 The author, contrary to an opinion he formerly entertained, 

 is now disposed, with Gerlach and others, to regard these 

 bodies as a kind of " nerve-cells." The nerve-cells are 



