90 NUTRITION. 



material which is removed, or more than compensate for 

 this : or the process of removal may proceed faster than 

 the process of nutrition. It is, therefore, obvious that 

 nutrition cannot be held to mean the mere addition of new 

 matter to a living body. 



Suppose we now consider what actually occurs when 

 simple living matter, like an amreba, or a white blood- 

 corpuscle, or a pus-corpuscle, is nourished. Matter either 

 in a state of solution or capable of being readily dissolved 

 passes into the matter of which the living body is composed. 

 Some of the constituents become part of the living body, 

 while others are given off. The living body then increases 

 in size. It is nourished and grows. In other instances, as 

 in many of the lower vegetable organisms, and in the ele- 

 mentary parts or cells of the higher, a coloured material or 

 matter having some peculiar properties is formed while the 

 process of nutrition is proceeding. Now, this matter did 

 not exist in the pabulum, nor was it to be detected in the 

 living matter which absorbed the pabulum, but it has 

 resulted from the death of the living matter under certain 

 conditions. In this case, then, the pabulum is first changed 

 into living matter, and the living matter into the coloured or 

 other formed material. In some instances this formed 

 material accumulates in the elementary part itself, as in the 

 case of starch in vegetable cells and fat in animal cells, 

 and there is a gain in weight. In other cases the formed 

 material passes away from the germinal matter as fast as it 

 is produced, dissolved in fluid or in a gaseous state, and no 

 alteration in weight occurs, although a large quantity of 

 nutrient matter is taken up. 



