464 THE BIOLOGICAL BASIS OF INDIVIDUALITY 



ferentials which help to produce the autogenous or, more generally, the 

 organismal tissue equilibrium, and which are present throughout the various 

 parts of the organism. They represent a second unity and are the foundation 

 of another type of individuality which, in contrast to the mosaic type, might 

 be designated as the essential individuality. From a genetic point of view, 

 tissue and organ characteristics, as well as individuality and species differ- 

 entials, ultimately depend upon the genetic constitution of individuals and 

 species and there is therefore a close relation between these two factors ; 

 however, the number of genes determining them, and perhaps also the 

 character of the individual genes which enter into their composition, differ, 

 and there is therefore no complete parallelism between organ characteristics 

 and organismal differentials. 



From the point of view of chemical structure, we may conceive of the 

 organ and tissue units as essentially consisting of a base of proteins which 

 have undergone phylogenetic and ontogenetic development. These proteins 

 may be assumed to be the bearers of characteristics common to all living 

 protoplasm ; but on this foundation there are built protein characteristics, first 

 of the largest animal group, to which the organism bearing these organs 

 belongs, and gradually there are added to these in sequence, constellations in 

 the protein, which are characteristic of class, order, family, genus, species, 

 strain and individual. These represent the organismal differentials. There 

 develops also in association with this basic protein structure, phylogenetically 

 and ontogenetically, a subdivision of each organism into a mosaic of organ 

 and tissue units, in which there are added to this protein base, new protein 

 constellations differing in different organs and tissues ; or looser associations 

 of the proteins with other, at first presumably very complex, substances of a 

 carbohydrate or lipoid character are acquired. In this case, likewise in 

 sequence, an increasing differentiation of these mosaic organ and tissue units 

 occurs, until in the end the most complex individual is established. Being 

 built upon the foundation of organismal differentials, these units contain the 

 class, order, species and individual characteristics which all parts of the 

 organism have in common; but there develop also in these chemical struc- 

 tures, smaller units which may become detached from the main substance, 

 and which as a rule show less or none of these organismal differentials ; 

 these function as enzymes, hormones, and certain other substances. In study- 

 ing the factors which bind the cellular constituents into the organ and tissue 

 units and which cause the interaction of different organs and tissues within 

 the same individual, specificities characteristic of class, order, species or 

 individual, may be present or may be lacking. In the latter case we can 

 exclude participation of the various organismal differentials in the reaction 

 or function of these organs and tissues. But if a function or reaction does 

 show such an organismal specificity, then the further question arises as to 

 whether this specificity is to be attributed to the organismal differential 

 chemical groups as such, or to other structural peculiarities of the organ 

 and tissue units, which presumably originally developed under the influence 

 of the organismal differentials, but which secondarily assumed a constitution 



