36 .B. G. HOSKIKS 



possibly for pituitary hormone, it would not seem to be a promising 

 method. The f difficulties and dangers of the method are more or less 

 obvious. 



Direct Application to Tissues. In many cases instructive results are 

 obtainable by application of endocrin extracts directly to the living 

 tissues. The clinical application of epinephrin to blanch the nasal mucosa 

 or the conjunctiva is a well-known procedure that illustrates this method. 

 The epinephrin spray for the relief of asthma is another example. Hart- 

 man has used a somewhat similar procedure in a study of the vaso- 

 dilator mechanisms. He applied epinephrin directly to various sympa- 

 thetic ganglia and noted the effects in the peripheral tissues. In the use 

 of the direct application method for experimental purposes the tissues 

 are ordinarily removed from the body and the extracts, either applied 

 to the surface or introduced through an isolated artery. One of the best 

 methods of determining the epinephrin content of a given fluid is to pass 

 it through the capillary circulation of the frog's hind legs. This is the 

 so-called Trendelenburg method. Mammalian tissues employed foT this 

 type of experiment are kept in warm oxygenated Tyrode's solution or 

 similar, fluid. In favorable cases they will survive for hours. Ott and 

 Scott published many investigations based upon this technique. The 

 rabbit intestine method for assaying epinephrin is a well-known example. 

 In such experiments, also, the quantitative factor should receive due re- 

 gard. A short segment of gut, for example, is but a small portion of the 

 total body tissue and would, if left in the body, be exposed to a corre- 

 spondingly small fraction of any given amount of circulating hormone. 

 In individual experiments the dosage should be correspondingly restricted. 

 Just how much allowance, however, should be made for decreased irrita- 

 bility of the test, tissues when removed from the body is unknown. 



(h-fjnn Grafting. In some instances organ grafting has been used to 

 augment the quantity of circulating hormones. In the early development 

 of the thyroid treatment of myxedema this procedure was successfully 

 employed. The literature contains many reports of attempts to alleviate 

 clinical symptoms by this method. An example which has recently evoked 

 much interest, especially upon the part of the laity, is the engrafting of 

 testes with the idea of rejuvenating elderly men. There are numerous 

 technical diflicultios, however, which limit the use of the method in prac- 

 tical experimentation and as a clinical procedure. The only way in 

 which -raftini: can he accomplished with anything like constant success 

 ; by the employment of the individual's own tissues (autografting), and 

 that procedure is ,f obviously restricted utility. The more closely related 

 are the host and the donor of the tissue, the more likely is the graft to 

 Transference from one species to another (heterografting) is 

 almost never successful. At best the tissue is soon absorbed and the net 

 result is equivalent to that of a parenteral injection. 



