SOURCES OF INFORMATION 21 



organic extracts have a distinct value in determining the nature 

 of organic function. 



The study of the chemistry of the organic extracts has 

 brought many important facts to light and promises to yield still 

 further results. The lipoid substances, which are of the highest 

 biological importance but to which, as yet, little attention has 

 been paid, deserve a closer investigation. 



There is one direction in which the extracts of the various 

 organs have been submitted to frequent tests. It has been found 

 that, when injected under the skin or into the veins of normal 

 animals, these substances exercise a more or less toxic action, 

 leading, in some instances, to death. Where, however, the 

 toxic action appears after intravenous injection only, the effect 

 cannot be regarded as in any sense specific. Most tissues contain 

 substances, in varying quantities, which promote the coagulation 

 of blood thrombokinesic substances and these, when injected 

 into the veins, may cause intravascular coagulation. It will 

 depend, therefore, upon the localization and the extent of the 

 thrombi whether there is more or less pronounced functional 

 derangement of the circulation and respiration, or whether the 

 condition becomes acute and terminates fatally. Tests of the 

 coagulability of the blood together with the post-mortem findings 

 may perhaps help the diagnosis. And it must be further borne 

 in mind that, however slowly and carefully the injections are 

 given, the introduction into the blood of substances having 

 thrombokinesic properties, whether in large or small quantities, 

 is very likely to provoke a negative action that, namely, which 

 prevents the coagulation of blood. 



The toxic effects of the subcutaneous or intraperitoneal 

 injection of organic extracts, on the other hand, may be regarded 

 as specific always supposing that the extracts have been prepared 

 from fresh organs under sterile conditions. But though the 

 method proves their toxicity, it does not permit of any definite 

 conclusion as to their physiological activity, for we are dealing 

 with substances, in exceptionally large quantities, which have 

 been obtained from the tissues by the mechanical destruction, 

 the literal breaking-up, of the cells. 



Far more reliable data are supplied by those activities of the 

 organic extracts which are purely physiological. Brown-Sequard's 

 discovery that the watery extract of the testicle his liquide 

 testiculaire possessed a marked tonic property, led to numerous 

 experiments, the object of which was to discover the physiological 

 activities of the extracts of various other organs. The most 

 important results were those obtained by Oliver and Schafer 

 (1894), who discovered the peculiar influence which certain tissue 

 extracts have upon the circulatory apparatus of normal animals. 

 The intravenous injection of certain organic extracts, as supra- 

 renal, pituitary, and renal, brings about a more or less charac- 



