4 SCHMIDT ON THE COMPARATIVE PHYSIOLOGY 



itions to the primary vegetable-cell (mother of vinegar, yeast- 

 cell), among which, with our scholastic definition of the notion 

 of animal and plant, we fall into a most remarkable difficulty, for 

 there are organic beings ivldcli combine the organic re- and de- 

 composing forces (StofFwechsel) and the chemical constituents of 

 the jilant vnth the locomotion of the animal! 



II. Special Observations and Deductions. 

 A. Nervous System. 



As is well known, we find a great uniformity in the minute 

 structure of the nervous elements of the Vertebrata, and, judging 

 from microscopic reactions, also in their chemical composition. 

 In all we find ganglionic bodies and primitive tubes ; these when 

 fresh are filled with homogeneous, highly refractive contents, 

 which after death coagulate and become granular. Alkalies make 

 the external outline of the ganglion-cells, also that of the primitive 

 fibre (cell-wall), swell, become pale, transparent, then disappear 

 (solution); the finely granular contents become converted into 

 large highly refractive drops, which are unchanged by acids and 

 alkalies, and are dissolved by tether ; acetic acid acts in a similar 

 manner, but does not cause true solution, which points out that 

 the wall of the primitive tube, as also that of the ganglion-cell, 

 is entirely composed of the cellular tissue of the adjacent sub- 

 stance; whilst fat, in a peculiar state of combination with albu- 

 men, forms the fluid contents. 



If we regard the difference between the ganglion-cell and the 

 primitive fibre as an essential morphological fundamental con- 

 dition of the mechanism of the nervous system generally, as the 

 originator and conductor of an active system of forces (nervous 

 agency, nervous principle, &c.), we should naturally find it 

 whei'ever the effects of this system are perceptible ; and, in fact, 

 we do find it in the animal series generally, so far as we are able 

 to trace these effects*. It is « ^non extremely probable that 

 this peculiar sys.em of forces requires a peculiar material sub- 

 stratum, in addition to a structurally distinct one, in order to be 

 apparent in its actions, consequently to be perceptible to us. 



* Valentin, Course and "rerniiuations of die Nerves, tab. 8; and Wagner, 

 Hundworterbuch, p. 700 (Craw-fisli). The latter author and Henie, Miiller's 

 Jrchiv, \M(i, p. 318 (Dhloma and Echinonhynchus). Henle, /{Ilgemeine 

 Anatomie, p. 7TA. Ehreiiberg, Description of a remarkable an hitherto un- 

 known Strutlure of the Brain, tab. 7. 



