98 NUTRITION. 



nervous textures the two last as perfect and, as far as we 

 can make out, far more delicate, elaborate, and beautiful 

 than any of the tissues of vertebrate animals are formed, 

 and with wonderful rapidity, in many of the lower creatures 

 quite destitute of a nutrient fluid containing bodies corre- 

 sponding to the red blood-corpuscles of the vertebrate 

 blood ; and that in all these cases the nutrient fluid is clear, 

 transparent, colourless, and contains a substance closely 

 allied to the albumen of serum, if not identical with it. 

 Different plants and animals may produce from the same 

 pabulum, and apparently under similar conditions, very 

 different substances ; and the different kinds of germinal 

 matter in the body of one of the higher animals give rise 

 to formed matters differing widely in structure, chemical 

 composition, and properties. 



2nd. That in man and the higher animals the develop- 

 ment of the tissues corresponds to the period of life when 

 the blood is not remarkable for the number or perfection of 

 its red blood-corpuscles. 



3rd. That certain morbid growths appear and increase 

 rapidly in cases in which the blood has for some time con- 

 tained a very small proportion of red blood-corpuscles. 



It seems, therefore, probable that the substances taking 

 part in the nutrition of all the different textures of the 

 body are furnished by the albuminous matter of the serum, 

 and that the production of muscle, nerve, fibrous tissue, &c., 

 depends not so much upon the characters of the pabulum 

 supplied as upon the converting powers of the germinal or 

 living matter which appropriates this. The substances 

 formed by germinal matter depend upon its vital powers 



