1898] RUDIMENTARY NERVOUS SYSTEM 339 
extremities and tie it by the other to a weight that can easily slide 
on a polished surface. At the vibration of the tube, that must be 
stretched beforehand, the weight is drawn by a quantity equiva- 
lent to the extent of the vibration. (Figs. 13 and 14.) 
2. By previously stretching a tube it may be induced to 
vibrate if connected in a point on its middle with a large 
globule of mercury (nervous termination), the vibrations of which 
start those of the tube; the locomotion of the weight along the 
table is the issue of all this. (Figs. 13 and 14.) 
This experiment may be considered as a difficult one on account 
of the computations indispensable to determine the degree of length 
of the tube and that of the weight which it must attract. 
Perhaps the vibration of a muscle is due to the discharges of 
carbonic oxide. 
(c) Acceleration of the pulsatile wave as observed by Landois 
in elastic tubes previously filled with water.—This too is easily 
observed in threads of mercury and serves to elucidate the question 
concerning certain reflexes that are simply the result of several suc- 
cessive excitations (ejaculation). A. L. HERRERA. 
Mexico, May 1st, 1898. 
(To be continued.) 
