28 R. G. HOSKINS 



substance by 'mouth or in various other ways, grafting into the body 

 viable endocrin tissue, or increasing the output from the individual glands 

 by massage or stimulation of their secretory nerves. A considerable 

 amount of valuable information has also been obtained from the study 

 of human beings or animals in which spontaneous overactivity of the 

 various glands occurs. 



Functional deficiencies can be created by gland extirpations, by 

 injecting substances to cause bland infarcts in the glands or by ligating 

 the blood vessels supplying the organs in question. Clinical observations 

 of patients with spontaneous or surgical gland deficiencies are also of 

 great value. Some of our most valuable data have been obtained from 

 such observations. 



Augmentation of Hormones. Intravenous Injections. Oliver and 

 Schafer's early experiments on the effects of suprarenal extracts admin- 

 istered intravenously made a profound impression and led the way to a 

 great number of other experiments of a similar sort with many gland 

 substances. The method is relatively easy and direct and, upon superficial 

 consideration, well calculated to afford important data in endocrin physi- 

 ology. Many investigators have utilized the method, however, with scant 

 appreciation of the numerous pitfalls with which it is beset, and have 

 drawn sweeping conclusions that the data secured by no means justified. 



The numerous possible sources of error in such experiments were early 

 recognized and pointed out. Gley in 1899 wrote: "It is necessary to ask 

 oneself if all the glands in question normally produce substances identical 

 with those the actions of which are manifested by their extracts. In fact, 

 the substances contained in the extracts may not exist in the living gland- 

 ular tissue ; furthermore nothing proves a priori that, if they are formed in 

 the living gland, they regularly leave it by the blood vessels in order to 

 exercise their influence on the different arterial regions of the organism. 

 It is necessary that the demonstration given for the suprarenal bodies be 

 also supplied for the other glands" (Gley, 1917). 



In 1S!U) Lewandowsky also pointed out that we cannot draw any 

 valid conclusion as to the action of any organ in the body from the effects 

 of extracts of that organ injected into the blood. 



Biedl has also warned of the fallacies inherent in sweeping deductions 

 from this type of experimentation. "'In order to prove conclusively that 

 in a given organ extract a hormone is contained, which results from the 

 endocrin activity of that particular organ, it is necessary first to establish 

 two postulates, which, in the present state of our knowledge, offer great 

 difficulties. First it is essential to secure a thorough knowledge of the 

 chemistry of the active substance. In this attempt much remains yet to 

 he done. A second and equally important postulate lies in the proof that 

 any given active substance demonstrated in the organic extract is produced 

 in the gland during life and is discharged into the circulation." 



