1898] RUDIMENTARY NERVOUS SYSTEM 337 
face supérieure devient & son tour électro-négative et reste ainsi 
pendant quelque temps.” * 
10. Excitants work either by disorganising the nervous textures 
or by a subtraction of water, that is, either by mechanical acts of 
disassociation or else by a modification in the density of the axis- 
band, or even of the neuroplasma itself. The influence exercised by 
interstitial water on the excitability of nerves appears to be quite 
evident, the mere fact of a nerve’s desiccation rendering it inexcit- 
able, though it is susceptible of recovering its physical and physio- 
logical properties when it has retaken by imbibition the quantity of 
water necessary for the discharge of its functions. Morphia may 
perhaps work by modifying the state of hydration of the neuro- 
plasm. It is likewise possible that the blood’s circulation and its 
state of concentration have an indirect influence on the velocity of 
nervous transmission. (Experimental studies of Mosso.) 
11. Most acids work as excitants if apphed to nerves. This 
point being settled, I can further state that a similar result is to be 
obtained by applying to the point of an artificial nerve of mercury 
and lead a little chromic or azotic acid, either concentrated or 
diluted. This also produces: (a) Contraction and tumultuous 
movements. (b) Production of waves, by discharge of nitrogen 
dioxide. This is certainly one of the most weighty demonstrations 
of my theory. 
The neuroplasm, the axis-band in general, ought to vibrate 
under the influence of acids, because the chemical action practised 
by the latter on albuminous matters must originate the shocks and 
vibrations attendant on the subtraction of water, discharge of carbon 
dioxide, ete. 
It is needless to observe that the movements of the artificial 
nerve of mercury and lead can be explained by the action of gas. 
when the chromic acid is applied. The bioxide of nitrogen slowly 
issuing from the bottom of some drops of nitric acid (1 in 10 of 
water), placed on the surface of the metal, begins to whirl round, 
after the manner of infusoria, or to produce some amoeboid move- 
ments that are extremely curious.” 
12. Physiologists are all of opinion that bile is one of the 
nerve’s excitants. 
In certain parts of the nervous system the continual vibrations 
observed may be due to the excitant action of oxygenated blood, by 
a discharge of carbon dioxide. 
13. Rough excitations have the power of effecting the nerve's 
vibrations, while slow and gradual excitations are unable, in spite of 
1 Revue Scientifique, Juillet ’ Décembre 1882, p. 735. ’ 
2 Note the amoeboid movements that Biitschli observed in foams and Préaubert im 
globular rays. ‘‘La vie mode de mouvement.” Paris, 1898. 
DA 
