226 THE BIOLOGY OF THE FROG chap. 



from the peritoneum, while the *' central cells " are generally 

 regarded as modifications of the cells of the sympathetic 

 ganglia. In the higher vertebrates the central cells form a 

 single mass which is surrounded by a definite cortex, but in 

 the frog they are scattered through the cortical cells in an 

 irregular manner. 



Abelous and Langlois found that if both adrenals of the 

 frog were destroyed, the operation was soon followed by fatal 

 effects ; but if only one adrenal was destroyed, the animal 

 would continue to live. If after the destruction of both 

 adrenals portions of one of the bodies were transplanted in 

 the dorsal lymph space, life was maintained for a consider- 

 ably longer period than would otherwise have been possible. 

 It is well known that the adrenals produce an internal secre- 

 tion upon which the Hfe of the organism is dependent. This 

 material (adrenalin, epinephrin) may be extracted from the 

 bodies and its physiological action tested. It has been 

 much experimented with among higher animals, and is now 

 used to a considerable extent in medicine and surgery. It 

 has the property of greatly increasing blood pressure by 

 causing a strong contraction of the smooth muscle fibers of 

 the blood vessels. 



Experiments on the effects of the extract of the adrenals 

 of the frog show that this substance has much the same 

 properties as among mammals, ^yhen injected into the 

 blood of a mammal, it produces a marked rise in blood pres- 

 sure ; and, on the other hand, injection of the extract from 

 the mammalian gland into the frog produces very marked 

 results, which may be fatal if the dose is large. Moore and 

 Vincent found that " after injection of a glycerin extract 

 equivalent to about .5 g. of the fresh gland into the 

 dorsal lymph sac, paralysis immediately comes on. . . . 

 With larger doses there are spasms and fibrillary twitchings 



