THE LAW OF LIKEXESS, AXD ITS WORKING. 227 



parts resembling those from which they were derived. The 

 curious phases of reproduction in the plant-lice, in which, it 

 will be remembered, female insects were seen to be capable 

 of producing generation after generation of beings resembling 

 themselves without the intervention of the opposite sex, is 

 likewise explained by the supposition that gemmules aggre- 

 gate in quantities in the egg-producing organs of the insects. 

 These gemmules are further regarded as being charged with 

 the power of perpetuating the likeness of the stock from 

 which they were originally derived, and are simply transmitted 

 from one generation to another, until, through some more 

 special modification, the periodical production of fertilised 

 eggs in autumn is once more illustrated. The exact nature 

 of " alternate generations " of the zoophytes and salpae 

 becomes clear to us if we presume that the gemmules of the 

 producing form, such as the zoophyte, are multiplied and 

 specially developed to form the jelly-fish bud, which finally, 

 as we have seen, is launched abroad charged with the task 

 of reproducing the zoophyte. Each egg of the jelly-fish 

 contains thus the gemmules inherited from, and which 

 convey the likeness and form of, the zoophyte ; the special 

 development of new beings seen in this case presenting a 

 contrast to the ordinary increase of the single zoophyte by 

 budding. The metamorphoses or changes which animals 

 undergo in passing from the egg to the adult state well 

 illustrated by the insect class can similarly be explained by 

 the deductions of pangenesis, if we suppose that the 

 gemmules which tend to form the perfect being undergo a 

 progressive development, and a gradual elaboration in the 

 earlier stages of the process. And we can the more readily 

 apply this reasoning to the explanation of the manner in 

 which the winged butterfly, for example, is evolved from the 

 caterpillar, when we find that within the chrysalis-case or 

 cocoon the body of the larvae is literally broken down and 

 resolved into atomic parts, whilst, by a wondrous process of 

 reconstruction and rearrangement of these atoms, the perfect 

 insect is in due time formed. Metamorphosis, in this 



