210 SEA-SIDE STUDIES. 



child, contains them in a condition perfectly useless, as far as 

 the direct and immediate nourishment of the child is con- 

 cerned : until the milk has undergone the digestive process, 

 namely, a succession of chemical decompositions and rccom- 

 ]>i>>itions, it is no more competent to nourish tlie muscles, 

 bones, and nerves of the child, than so much chalk and water, 

 wliich is delusively sold as milk in virtuous cities. The 

 mutton chop, too, which we justly reckon such excellent 

 food, is only "food potential;" it must undergo a very 

 curious series of changes before it can be converted into blood. 

 Nor is the business finished there. We are erroneously 

 accustomed to consider blood as the final stage of food, pre- 

 vious to its assimilation. Physiologists trace the story of 

 Digestion up to this point, and there leave it ; as story-writers 

 leave their heroes married, thereby indicating that nothing 

 more remains to be said. But just as marriage is the begin- 

 ning of a new act in the drama, and the act in which all life 

 culminates, so is this blood-formation but the commencement 

 of a new series of changes, and these the most important. I 

 think it can be shown that the blood itself is not more im- 

 mediately and directly assimilable than the mutton chop from 

 which it was formed. In its passage through the walls of 

 its vessels, it undergoes specific changes, fitting it for assimi- 

 lation ; without such changes it is not assimilable ; blood, as 

 blood, nourishes no tissue, but lies on it like any other foreign 

 substance which must be got rid of by re-absorption into the 

 veins — as we see when a vessel is ruptured, and the blood 

 gets deposited in tlic parenchyma. Blood is, in fact, as 

 Bergmann and Leuckart well express it, "a depot of assimil- 



