CLASSIFICATION OF ALBUMINS 351 



that the albumins of an organism may change chemically owing to 

 partial decomposition during metabolism, has been disproved by the 

 self-same authors." (Cohnheim.) 



Cohnheim's views are not shared by the author, for the systematic 

 classification of animals and of plants recognises the existence of a 

 few large units, which are then subdivided into more numerous 

 sub-units, and these ultimately through ' general ' and ' special ' into 

 1 individual ' units. Every one of these units is characterised by 

 two sets of definite features, the one of which is common to all, while 

 the other is specific of each unit. Thus all plants and animals have 

 nuclei and cell-plasm in common, the activities of which are inversely 

 proportional to one another. Amongst all animals from Vorticella to 

 Man certain contractile tissues have an alternating arrangement of 

 clear and dim stripes, and the unformed blood of an octopus reacts 

 to certain micro-chemical methods, as does the formed blood of 

 vertebrates ; J the nerve-cells of amphibians and mammals closely 

 resemble one another in possessing certain aggregations of nucleo- 

 proteid matter, the so-called Nissl-granules, in their cell-plasm, and 

 so on. Therefore the resemblance of animals to one another as far 

 as certain histological characters are concerned is very great, and yet 

 we must not overlook the differences. 



As lower organisms by evolution give rise to higher ones, so does, 

 for example, simple collagen by evolution give rise to the stages of 

 cartilage, calcified cartilage, and bone. On the assumption, which 

 Cohnheim believes to be allowable, that the gelatin-basis of the tissues 

 just enumerated is the same, the differences in the final product must 

 be due to the presence of chondro-sulphuric acid, as in cartilage, or to 

 that of metaphosphoric acid, as in bone. The question naturally sug- 

 gests itself : Whence comes chondro-sulphuric acid or the metaphosphoric 

 acid 1 These radicals must have been formed somewhere ; if albumins 

 play no part in their production, then they must be derivatives of 

 nuclear activity. In any case the special selective activity shown 

 by collagen in certain regions of the body must be due to a difference 

 between this particular collagen and that occurring elsewhere there 

 must exist chemically different collagens. 



We may safely assume that in their coarse chemical framework all 

 groups of plants and of animals agree, and that those characteristics 

 which are peculiar to each individual species are produced by trans- 

 formations and substitutions in ' side-chains ' ; and further, that this 

 change is only possible by a new arrangement of the different 

 amino-acids both as regards the relative quantities in which each 



1 Mann, Physiological Histology, 1902, p. 217. 



