154 



Scientific Proceedings (39). 



97 (507) 



The development and function of the heart in embryos 

 without nerves. 



By DAVENPORT HOOKER. (By invitation.) 



[From the Sheffield Biological Laboratory of Yale University, 

 New Haven, Conn.} 



The somatic muscle in frog embryos, from which the cord has 

 been removed, was proven by Harrison (1904) to develop and 

 differentiate normally. Such muscle tissue, when stimulated by 

 an extremely fine needle point, will contract provided the needle 

 perforates the skin and penetrates the muscle itself. The response 

 produces a single quick bending of the body toward the side stimu- 

 lated, the point of stimulation being the center of contraction. 

 Other experiments show that the muscle tissue cannot be stimu- 

 lated through non-nervous protoplasmic connections. 



In frog embryos from which the entire nervous system has 

 been removed at the stage immediately following the closure of 

 the neural folds, the heart functions normally. The rate is, how- 

 ever, slightly lower than in normal individuals. Microscopic ex- 

 amination shows that the cardiac muscle of such embryos has 

 differentiated normally. The condition of this tissue very closely 

 parallels the results obtained by Harrison in somatic muscle. 



The results of these experiments show that, in the total absence 

 of the nervous system, somatic muscle is directly irritable, the 

 heart will function normally and cardiac muscle like somatic muscle 

 will differentiate normally. 



98 (508) 



The toxicity of amyl acetate. 1 



By WILLIAM SAL ANT. 



[From the Bureau of Chemistry, U. S. Department of Agriculture.] 



From four to six cubic centimeters per kilo of amyl acetate 

 injected into frogs caused paralysis and coma in from 15 to 30 

 minutes. These symptoms lasted 24 hours, with final recovery. 

 In some cases such doses proved fatal. Larger doses were in- 



'Published by permission of the Secretary of Agriculture. 



