CHYMOSIN 27 



suggest that the hemorrhages in the mucosa as well as 

 thromboses may not be primary lesions in the production of 

 ulcers, but rather secondary to and produced by the 

 ulceration. 



Chymosin. A short review of the problem of the lab- 

 coagulation will serve to conclude the present lecture. 



It may be confidently asserted that the question of the 

 rennet-ferment or chymosin is the oldest physiological- 

 chemical problem which has concerned mankind. For, 

 many, many thousands of years ago, when humanity was not 

 interested in observation of nature and in contemplations 

 about natural philosophy, the nomadic herdmen were well 

 acquainted with the use of the gastric mucous membrane in 

 curdling milk. 



A mere glance over the extremely extensive literature 

 dealing with the lab process gives one the impression of an 

 impenetrable thicket of apparently diametrically opposed 

 observations and theories, just as in the study of blood 

 coagulation. 



Starting with the observations of Hammersten many 

 attempts have been made to outline the lab-process as a 

 double-phased one in which the bulk of the casein is first 

 changed into paracasein, which upon the addition of a suf- 

 ficient amount of calcium salts is thrown down as the almost 

 insoluble calcium paracaseinate or cheese, a small part of 

 the protein remaining, however, in solution as an albumose- 

 like whey-albumin from a coincident splitting process. This 

 simple formulation has not entirely harmonized, however, 

 with all the experimental findings of a large group of investi- 

 gators who have been interested in the subject, relating to 

 ferment-kinetics, the physical-chemical characteristics of 

 milk, the inhibition and stimulation of the lab-process by 

 various agents, to parachymosin and prochymosin, the part 

 played by calcium salts, antiferments, and other comparable 



