PHYSIOLOGICAL INTEGRATION XN AKIMALS. <169 



rvtfects tho nutrition and efficiency of organs remote from 

 the place of injury. Then where, as in further-developed 

 creatures, there exists an apparatus for propelling the blood 

 through, these ramifying channels, injury of a single one 

 will cause a loss of blood that quickly prostrates the entire 

 organism. Hence the rise of a completely-differentiated vas- 

 cular system, is the rise of a system which integrates all 

 members of the body, by making each dependent on the in- 

 tegrity of the vascular system, and therefore on the integrity 

 of each member through which it ramifies. Iq 



another mode, too, the establishment of a distributing 

 apparatus produces a physiological union that is great in 

 proportion as this distributing apparatus is efficient. As 

 fast as it assumes a function unlike the rest, each part of an 

 animal modifies the blood in a way more or less unlike the 

 rest, both by the materials it abstracts and by the products it 

 adds ; and hence the more differentiated the vascular system 

 becomes, the more does it integrate all parts by making each 

 of them feel the qualitative modification of the blood which 

 every other has produced. This is simply and conspicuously 

 exemplified by the lungs. In. the absence of a vascular 

 system, or in the absence of one that is well marked off 

 from the imbedding tissues, the nutritive plasma or the crude 

 blood, gets what small aeration it can, only by coming near 

 the creature's outer surface, or those inner surfaces that are 

 bathed by water ; and it is probably more by osmotic ex- 

 change than in any other way, that the oxygenated plasma 

 slowly permeates the tissues. But where there have been 

 formed definite channels branching throughout the body; 

 and particularly where there exist specialized organs for 

 pumping the blood through these channels ; it manifestly 

 becomes possible for the aeration to be carried on in one part 

 peculiarly modified to further it, while all other parts have 

 the aerated bjood brought to them. And how greatly the 

 differentiation of the vascular system thus becomes a means 

 of integrating the various organs, is shown by the fatd 



