238 Animal Life and Intelligence. 



origin. Superabundant vigour may well, I think, have 

 been a source of origin^ not only of secondary sexual charac- 

 ters, but of many other forms of variation. 



And while these forms of variation may be the special 

 prerogative of the male, we may perhaps see, in super- 

 abundant female vigour, a not less important source of 

 developmental and embryonic variations in the offspring. 

 The characteristic selfishness of the male applies his surplus 

 vitality to the adornment of his own person; the charac- 

 teristic self-sacrifice of the mother applies her surplus 

 vitality to the good of her child. Here we may have the 

 source and origin of those variations in the direction of 

 fosterage and protection which we have seen to have such 

 important and far-reaching consequences in the develop- 

 ment of organic life. The storage of yolk in the ovum, the 

 incubation of heavily yolked eggs, the self-sacrificing de- 

 velopment in the womb, the elaboration of a supply of 

 food-milk, — all these and other forms of fosterage may well 

 have been the outcome of superabundant female vigour, 

 the advantages of which are thus conferred upon the 

 offspring. 



We may now proceed to note, always remembering the 

 paramount importance of the organism, some of the effects 

 produced by changes in the environment. 



The most striking and noteworthy feature about the 

 effects of changes of climate and moisture, changes of 

 salinity of the water in aquatic organisms, and changes 

 of food-stuff, is that, when they produce any effect at 

 all, they give rise to definite variations. Only one or 

 two examples of each can here be cited. Mr. Merrifield,* 

 experimenting with moths {Selenia illunaria and S, illus- 

 traria), finds that the variations of temperature to which 

 the pupae, and apparently also the larvae, are subjected 

 tend to produce " very striking differences in the moths.'* 

 On the whole, cold *' has a tendency, operating possibly 

 by retardation, to produce or develop a darker hue in 



* "Incidental Observations in Pedigree Moth-breeding," F. Merrifield. 

 Transactions Entomological Society, 1889, pt. i. p. 79, et seq. 



