ORGANS AND TISSUES AS CRITERIA 461 



differences in the corresponding regional smells, although it is not certain 

 from Lohner's report that this fact has been experimentally established. 

 However, if this view should be correct, then it would follow that the scent 

 of an individual is not only a composite effect of his multiple regional scents, 

 but there is, besides, a specific feature attached to each regional scent of a 

 given individual. It is of interest also that, secondarily, these scents are 

 influenced by the functioning of the sex organs and that they become quanti- 

 tatively more pronounced at the time of puberty. It has been found, more- 

 over, that likewise the distribution of the openings of the sweat glands are 

 individual characteristics in man. 



We see, then, that in the case of individual scents, as in the case of skin 

 patterns, we have to deal with complex effects which represent the result of 

 the composite actions of more elementary units. Organismal differentials are 

 not involved in either instance, but rather special substances or structures 

 inherent in certain tissues or organs; these localized characteristics are not 

 inherent equally in all, or even almost all, the tissues of an individual, but 

 they are specific for each individual. They must therefore be included among 

 the mosaic characters which distinguish individuals. 



III. We have discussed more in deta-il two inherited conditions in man as 

 examples of individual differences of organs, or tissues, their structures and 

 chemical characteristics. But similar differences are found also between the 

 other analogous organs and tissues in different individuals and species. On 

 the other hand, analogous organs have essential features as to metabolism 

 and function in common in different species, especially in more nearly 

 related ones; the differences which they show become individualized the 

 more, the further advanced these species are in the phylogenetic and onto- 

 genetic scale. 



In mice it can be demonstrated that in different, closely inbred strains, 

 various organs such as thyroid and corpus luteum, differ in their structural 

 and, therefore, also functional age curve; likewise, notwithstanding the 

 essential similarity in structure of vagina and uterus, the structure of the 

 maternal placenta in nearly related species shows some notable differences. 

 Furthermore, different species of fresh-water fishes present characteristic 

 differences in their reaction to differences in C0 2 pressure in the water in 

 which they live (Irving). The structure and physiologic reactions of the red 

 corpuscles, the crystalline forms of hemoglobin differ in different species, 

 and these differences are, to a certain extent, correlated with the phylogenetic 

 relationship of the species from which they are derived (Reichert and 

 Brown). 



As a further example of this type of specificity, we might mention the 

 manner in which various species or classes of animals react against phenyl- 

 acetic acid when it is introduced into their bodies. In the majority of mam- 

 mals, including monkeys, this substance combines with the aminoacetic acid 

 (glycin), and it leaves the body in the form of phenaceturic acid. In man 

 and in anthropoid ape (chimpanzee) phenylacetic acid combines with glut- 

 amine, the amide of glutamic acid, a dicarboxy acid, to form phenylacetyl 



