THE SYMPATHETIC SYSTEM 11 



liquids of endocrine origin and the possibility of their use 

 in therapeutics (Brailsford Robertson). 



THE PHYSIOLOGICAL STUDY of the internal secretions 

 gives us much more definite knowledge than either histology 

 or chemistry, but without these two it must remain incom- 

 plete. We are able to study from it the specific action of 

 substances extracted from a gland or from a vein afferent 

 from this organ. By this method it has been possible to 

 study the character of the venous blood of the suprarenals 

 and obtain the characteristic cardio tonic action. In the 

 majority of cases all that can be done is to study the action 

 of extracts of organs. This is the method which has given 

 the best results and from which organo therapy has been 

 deducted. We must not, however, make statements too 

 specific as regards these. Gley has shown how careful we 

 have to be. The isolation of extracts of organs is always 

 complex. What do these substances represent? Do 

 they exist in the living organ; are they excreted in the 

 venous blood? 



If so, are they excreted all at once or in small doses? 

 The action of the extract cannot be the same as that of the 

 blood coming from the veins of the organ and the pathol- 

 ogist must be careful not to make any rash deductions, 

 basing his conclusions on the action of an organic extract 

 and comparing it to certain symptoms noted in certain 

 affections. We must also keep in mind the toxicity of 

 extracts of organs. This toxicity varies according to the 

 method of preparation and can become more important 

 than the specific action of the extract of the organ. It is 

 also probable that the various manipulations which are 

 performed in order to lessen the toxicity, can also modify 

 the action. It is possible that the administration of 

 extracts of organs be followed by anaphylactic phenomena, 

 since these extracts contain foreign proteins or inversely 



