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less, or vagrant, blood-corpuscles as probably media of 

 conjugation or reparation, but acknowledge their func- 

 tion to be as yet quite unknown ; while Rindfleisch, 

 characterizing the spleen as the grave of the red, and 

 the womb of the white, corpuscles, evidently refers the 

 latter to the former. This, indeed, is a matter of direct 

 assertion with Preyer, who has " shown that pieces of 

 red blood-corpuscles may be eaten by the amoeboid cells 

 of the frog," and holds that the latter (the white cor- 

 puscles) proceed directly from the former (the red cor- 

 puscles) ; so that it seems to be determined in the 

 mean time that there is no proof of the reverse being 

 the fact. 



In function, then, to resume, some protoplasm is va- 

 grant, and of unknown use. Some again produces pep- 

 sine, and some fat. Some at least contains pigment. 

 Then there is nerve-protoplasm, brain-protoplasm, bone- 

 protoplasm, muscle-protoplasm, and protoplasm of all 

 the other tissues, no one of which but produces only 

 its own kind, and is uninterchangeable with the rest. 

 Lastly, on this head, we have to point to the over- 

 whelming fact that there is the infinitely different pro- 

 toplasm of the various infinitely different plants and 

 animals, in each of which its own protoplasm, as in the 

 case of that of the various tissues, but produces its 

 own kind, and is uninterchangeable with that of the 

 rest. 



It may be objected, indeed, that these latter are ex- 

 amples of modified protoplasm. The objection of 

 modification, as said, we have to see by itself later ; 

 but, in the mean time, it may be asked, Where are we 

 to begin, not to have modified protoplasm ? We have 

 the example of Mr. Huxley himself, who, in the nettle- 



