CHAPTER X. 



SPECIALITIES OF THESE RELATIONS. 



I 356. Tests of the general doctrines set forth in preceding 

 chapters, are afforded by organisms having modes of life that 

 diverge widely from ordinary modes. Here, as elsewhere, 

 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 that expend very little for 

 self-support in comparison with allied creatures, a relatively 

 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 ItqfflesiacecB, 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 



