96 THURLOW C. NELSON 



gram. 



Ten styles, fresh 0.16 



Nitrogen, per g. of fresh style 



Water soluble 0.0011 



Precipitable 0.0061 



Total nitrogen 0.0072 



In criticism of Mitra's conception of the style as a mass of 

 pure enzyme, it may be urged that the evidence which he ad- 

 vances is inconclusive. The mere fact that the style substance, 

 kept under alcohol, lost in ferment power, proves nothing, for 

 it is well known that enzymes in general lose their activity on 

 long standing under such conditions. 



Furthermore, examination of the substance of a freshly formed 

 style with the dark stage condenser shows it to be composed 

 of small globules of fairly uniform-size, interspersed with many 

 very minute globules or particles, in the nature of colloid par- 

 ticles. It is probable that we have to do with an adsorption 

 phenomenon, the enzyme being borne on the surface of the 

 globules of albuminoid substance. 



It may be concluded, therefore, following Coupin ('00), that 

 the crystalline style is a structure of colloid nature, resembling 

 mucin, and containing an enzyme, or enzymes, of strong amylo- 

 lytic power. 



Nature of the gastric shield 



Finally, a few observations are necessary regarding the nature 

 of the gastric shield. Subjected to the biuret test, it rapidly 

 disintegrates under the action of the strong caustic. On the 

 addition of the copper-sulphate solution a purple color forms on 

 the surface, grading into a pink toward the interior. This would 

 indicate the presence of such substances as proteoses and pep- 

 tones. From the zonation of the colors it is probable that this 

 reaction is due to products of digestion absorbed by the shield. 

 From its consistency and action toward the common reagents it 

 is probably in the nature of chondrin. 



The shield is very resistant to the action of the digestive juices 

 of the stomach. I have invariably found it present in all living 

 specimens that I have examined. If kept in a test-tube with a 



