CHAPTER X. 



SPECIALITIES OF THESE RELATIONS. 



356. TESTS of the general doctrines set forth in preced 

 ing chapters, are afforded by organisms having modes of life 

 which diverge widely from ordinary modes. Here, as else 

 where, aberrant cases yield crucial proofs. 



If certain organisms are so circumstanced that highly- 

 nutritive matter is supplied to them without stint, and they 

 have nothing to do but absorb it, we may infer that their 

 powers of propagation will be enormous. 



If there are classes of creatures which expend very little 

 for self-support in comparison with allied creatures, a rela 

 tively-extreme prolificness may be expected of them. 



Or if, again, we find species presenting the peculiarity 

 that while some of their individuals have much to do and 

 little to eat, others of their individuals have much to eat and 

 little to do, we may look for great fertility in these last and 

 comparative infertility or barrenness in the first. 



These several anticipations we shall find completely 

 verified. 



357. Plants which, like the Raffle siaceae, carry their para 

 sitism to the extent of living on the juices they absorb from 

 other plants, exhibit one of these relations in the vegetal 

 kingdom. In them the organs for self-support being need 

 less, are rudimentary; and the parts directly or indirectly 

 concerned in the production and distribution of germs, con 

 stitute the mass of the organism. That small ratio which 

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