522 ON THE PHYSIOLOGICAL ACTION OF CASCA BAEK. 



2. In addition to the absence of the development of Bacteria 

 which is noticed when muscular tissue is placed in a watery 

 solution of the alcoholic extract, and which has already been 

 remarked upon, the structural changes which the muscular 

 tissue undergoes appear to consist in a fatty metamorphosis, 

 which at first simulates very closely that of ordinary fatty 

 degeneration, while the later appearances resemble those of the 

 more complete fatty changes which go on after tlie death of 

 a tissue, large oil-giobules and abundant crystals of the fatty 

 acids being everywhere found. 



3. It does not diminish the lifting-power of muscle in a 

 nerve-muscle preparation, nor when the irritation is applied to 

 the muscle itself, and it probably does not increase it; for 

 although apparently positive results were attained on the first 

 occasion when the lifting-power was experimented on, these 

 results were not borne out by further experiments. 



4. The muscle-curve given by a nerve-muscle preparation 

 taken from a frog poisoned by a large dose of casca apjjears to 

 be quite a normal one. 



5. It also exerts no action on the sensibility of muscle to 

 electrical stimulation if this sensibility be tried quantitatively 

 by estimating the weakest interrupted current which will pro- 

 duce a contraction. 



From all these results, then, it may be concluded that while 

 the drug produces a peculiar and characteristic change on 

 muscular tissue immersed in it for some days, it is not a muscle- 

 paralyzer. 



Action on Motok Nerves. 



If casca had any paralyzing action on the ends of motor 

 nerves similar to that of curare, it would be found that after 

 immersion in a solution of the drug the muscle would respond 

 to electrical stimuli directly applied to it, but not to those 

 applied to the nerve. In Experiment LII, however, the nerve 

 also is seen to preserve its irritability, and therefore we may 

 conclude that casca has no action on motor nerves. 



