THE PLASMA 157 



the substances injected. This specific character is not however by any means 

 absolute. 



If we add to what has been said above, that after the injection of an 

 agglutinating serum into an animal an antiagglutinating effect may be obtained, 

 after injection of a precipitating serum an antiprecipitating effect, after a 

 cytolytic serum an antilytic effect, it ought to be apparent without further dis- 

 cussion that under the influence of various chemical agents, extraordinarily 

 important and complex changes can be induced in the blood. 



These changes are produced in part by a special activity of different cells 

 of the body, developed by the attack, in part by certain leucocytes. 



There can be no doubt that all these changes are protective adaptations of 

 the ~body against harmful influences. Especially is this true of the antitoxins, 

 the bacterialysins, and agglutinins. 



The matter is not so clear with regard to the other lysins and the pre- 

 cipitins; but it is to be presumed that they also have some definite purpose. 

 It appears that they are specialized substances, which, like the antienzymes, 

 come down in the globulin precipitates ; but whether they are true proteid bodies 

 or are only attached to such, cannot be said definitely as yet. 



We must forego a presentation of the theoretical views which are held in 

 explanation of these phenomena, since a discussion of them would require too 

 much space. We would not, however, omit to mention the side-chain theory of 

 Ehrlich, since this has had a very stimulating effect on research in this field, 

 and has very successfully gathered together under one general point of view the 

 complicated phenomena which confront us in this province. 



Since the chemical processes in different organs are in many respects very 

 different, the blood returning by the vein must have a more or less variable 

 constitution according to the organ from which it flows. Analysis of these 

 different kinds of blood would be well calculated to give at some future time 

 very valuable conclusions as to the chemical transformations taking place in 

 the corresponding organs. At present however our information is quite too 

 inadequate for any discussion of the subject. 



The blood flowing from the different parts of the body is collected finally 

 in the two venae cavas and is emptied by them into the right heart, where the 

 different kinds of blood, not yet thoroughly mixed in the veins, are mixed 

 together; so that blood driven from the left ventricle to all varts of the 

 body is entirely homogeneous. 



B. COAGULATION OF BLOOD 



If blood be drawn directly from an open artery into a saturated solution 

 of magnesium sulphate, it can be kept for days without coagulating. The 

 blood corpuscles can be removed from such blood by filtering, by centrifugal- 

 izing, or simply by letting it stand, and in this way a fluid is obtained known 

 as the salt plasma (Alex. Schmidt). By precipitation with an equal volume 

 of saturated NaCl solution, there is thrown down a proteid body, the fibrino- 

 gen, which can be further purified by various means. Fibrinogen is soluble in 

 weak NaCl solution and its solution will keep at room temperature until 

 putrefaction sets in without showing a trace of coagulation. // however some 

 blood or blood serum be added to such a solution, fibrin formation takes place 



