PROTOPLASMIC STRUCTURE 31 



glucoproteids, and the enzymes, the first scarcely exist in primal or 

 undift'erentiated protoplasm, for they are little needed, respiration taking 

 place without the intermediation of hemoglobin for instance, one of 

 the chromoproteids. Of the glucoproteids, the chief is mucin. The 

 enzymes are numerous. Their functions are so various and they are 

 so small in amount that little is known about their composition, while 

 to describe their uses would be out of place here. We do not really know 

 that they are proteids. It is sufficient at this point if it becomes clear that 

 every organism probably contains as part of its substance these six classes 

 of proteids, in some degree and proportion. In the present state of con- 

 fusion concerning the relation of the proteids to organic function, it is a 

 great satisfaction to be aware that the master chemists, such as Fischer, 

 Bunge, Hoppe-Seyler, Hammarsten and Abderhalden, find as much 

 difficulty in forming a correct idea of these matters in their minds as 

 do those who look to their work and to their opinions for information. 

 Here more than almost anywhere else is it plain that physiology is far 

 from being as yet a science anywhere nearly " exact" so continually 

 does the "simple" prove infinitely complex. 



One other general consideration concerning the proteids should be 

 pointed out namely, the possibility that changes much more extensive 

 than has been supposed may normally take place in the chemical com- 

 ponents of a cell. This may be one reason why constancy of analytic 

 result has been found impossible namely, that there is no "constancy" 

 in the analyzed substances. The vital interactions in protoplasm are 

 so complicated that it is almost impossible to say how far-reaching cer- 

 tain changes may be, how many new substances are formed, how often 

 those which are present are changed back and forth in their qualitative 

 as well as in their quantitative compositions. If proteids are changed to 

 amino-acids and back again to proteids while passing quickly through 

 th3 thin wall of the intestine it is difficult to estimate the making and the 

 unmaking which a mass of protoplasm might occasion, given sufficient 

 time and space. 



The third sort of biogenic components or proximate principles we may 

 consider are the fats. The fats as found in the bodies of animals occur in 

 three pure forms, and as lecithin. These three are the triglycerides or 

 ethers of oleic, palmitic, and stearic acids, which are a series of acids 

 derived from monatomic alcohols by the process of oxidation. (Choles- 

 terin is a monatomic alcohol, also, found in every cell: formula, C 26 H 44 O.) 

 The first is a liquid at ordinary room temperature, while the others are 

 solids, melting at 45 C. and 60 C., respectively. They thus would be 

 more or less solid in the human body at a temperature of about 38 C., 

 were they not held in solution by the olein, which solidifies only at five 

 degrees below the centigrade zero. There are two ways in which these 

 triglycerides and their compounds are parts of animals. They are 

 deposited in masses in bone-marrow, under the skin, and elsewhere in 

 the bodies of many animals. In minute quantity and in forms as yet 

 hardly known they enter, it seems probable, into the composition of the 



