REPORT OF THE SECRETARY. 25 



at by the author ; and though some of them may have been previously 

 obtained, yet they will serve even in these cases to verify the results 

 of other investigations. 



The amount of water in the blood is greatest in the invcrtebrata. 

 Among vertebrate animals it is greatest in fishes and aquatic reptiles, 

 and least in serpents, birds, and mammals. It would appear, as a 

 general hiw, that as the organs of the animal are developed, and the 

 temperature and intellect correspondingly increased, the blood be- 

 comes richer in organic constituents. The blood of serpents, at first 

 sight, appears to form an exception to this conclusion ; the larger 

 amount of solid matter existing in their blood is^ however, accounted 

 for by the fact that they seldom or never drink wateie, and as they 

 are constantly, though slowly, evaporating this fluid, the blood must 

 necessarily become concentrated and yield a larger quantity of solid 

 constituents upon analysis. The proportion of the constituents of the 

 blood of mammalia varies as much in individuals of the same species 

 as in those of remotely separated genera. In the invertebrate ani- 

 mals the number of blood corpuscles is very small in comparison with 

 that in the vertebrata. The fibrine constitutes a remarkable index of 

 the vital, organic, and intellectual endowments of animals. In the 

 whole of the invertebrate kingdom it is absent, except in a few of the 

 most highly organized. In the lower order of the vertebrata, as 

 fishes and batrachians, it is soft, unstable, and readily converted into 

 albumen. The proportion of fixed saline constituents in the blood is 

 remarkably uniform throughout the whole animal kingdom. Among 

 the vertebrate animals the greatest amount of mineral constituents 

 is found in fishes and reptiles inhabiting the salt water. In every 

 instance during abstinence from nourishment, the water of the blood 

 diminishes more rapidly than the solid portions. The rapidity of the 

 consumption of the watery element, and the consequent concentration 

 of blood, is connected with the vital and physical condition of the ani- 

 mal, being more rapid in the case of those of warm blood . The cor- 

 puscles waste during starvation, as well as the other components, thus 

 proving tliat they have an important office to fulfil in the support of 

 the tissues and organs of the living animal. The fibrine relatively 

 increases during starvation and thirst. The fat of the body wastes 

 more rapidly than any other of the tissues. The continuance of life of 

 the animal during starvation and thirst is inversely proportional to the 

 rapidity of change of its elements, and, as a necessary consequence, to 

 its temperature and organic development. The relative weight of the 

 heart to that of the body was found proportionably smaller in fishes 



