INFLUENCE OF CERTAIN PHYSIOLOGICAL CONDITIONS. 337 



This may be due to the fact that the cats of the New World in general lead 

 a more active life than those of the Old World, or that they live in general 

 in a cooler climate, and therefore use more oxygen than the Old World 

 species. 



The influence of food may be seen in the bloods of animals that are 

 herbivorous as compared with those which are graminivorous. Among the 

 rodents, the hares and rabbits are herbivorous, and their hemoglobins are 

 rather soluble, being comparable in solubility to the hemoglobins of 

 the herbivorous ungulates. The hemoglobins of the squirrels, on the other 

 hand, which are rodents that live largely on seeds and nuts, are relatively 

 much less soluble, while the hemoglobins of species of rodents that live on 

 the leaves and roots of plants and also on seeds, such as the porcupine and 

 the ground-hog, have hemoglobins that are intermediate between these two 

 extremes. When we compare other animals, such as the gallinaceous birds, 

 which live on seeds very largely, with the seed-eating rodents, we see, 

 however, that the hemoglobins are as soluble or even more soluble than those 

 of the hares and rabbits. 



The condition of the hemoglobins in the corpuscle: 



It would seem strange that with substances such as the hemoglobins, 

 which in many cases are relatively rather insoluble, crystallization is not a 

 common occurrence in the erythrocytes in the living animal or in freshly 

 drawn blood. In fact, crystallization under these conditions rarely occurs, 

 although it is common, judging from the records of various investigators, 

 in blood that is not fresh. The question then arises, what keeps this sub- 

 stance, even in cases where it is readily cry stalliz able, from solution, in this 

 uncrystallized form in the corpuscles? The typical condition of matter of 

 definite composition is crystalline, but the typical condition of living mat- 

 ter is the amorphous condition, or, as it is generally called, the "colloidal" 

 condition. In inorganic compounds and in non-living organic compounds 

 amorphous and colloidal conditions can be maintained by preventing the 

 composition from becoming definite, as by adding to it or withdrawing from 

 it substances that would make it definite. To prevent glass from crystal- 

 lizing, care must be taken to keep the fusion of a composition that does 

 not approach too nearly to a definite silicate. In alloys, crystallization is 

 prevented in much the same way by avoiding mixtures in which the ratio 

 of the metals is a regular molecular ratio. In substances which crystallize 

 with water of crystallization, an amorphous or colloidal condition can often 

 be produced by not having enough water present to form the normal crystal. 



The hemoglobin in the corpuscle is almost universally regarded as 

 being in some way combined with the stroma of the corpuscle, and it seems 

 to us probable that this union is in the nature of a compound comparable 

 to an alloy or to glass in that it is of indefinite composition; or, that the 

 hemoglobin may be held in the corpuscle in such a way that, owing to the 

 osmotic properties of the stroma, there is a deficiency of the fluid of crystal- 

 lization to form the definite compound that can crystallize. In either case 

 the material does not crystallize because it is not of the proper composition 



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