THE BEGINNINGS OF LIFE. 87 



fall into shapes belonging to one or other of the ordi- 

 nary crystalline types of form. 



But the prevailing shapes of crystals and of organisms 

 respectively— those differences of form which are sup- 

 posed to be characteristic and peculiar to each — are ob- 

 viously referrible in part to the nature of the constituent 

 molecules, and in part to the nature of the medium 

 in which these molecules aggregate. The more closely 

 the molecules of the crystalloid and the medium in 

 which they unite approximate to colloidal complexity 

 and the kind of media in which organisms are found, 

 the more do the shapes of the crystalloid aggregates 

 resemble those of the simplest organisms. This has 

 been conclusively shown by Mr. Rainey's experiments ; 

 and they, together with other considerations now to 

 be mentioned, almost compel assent to the correctness 

 of the view already advanced by Mr. Spencer and 

 several others, to the effect that the shape and structure 

 of any organism is to be regarded as the result of 

 the play of the molecular affinities of the organizable 

 matter under the influence of the forces operative in its 

 medium — that, in fact, organisms are produced owing 

 to, and under the influence of, precisely the same laws 

 as those which give birth to and regulate the form 

 of crystals. Unless this be so, how are we to explain 

 the various cases of restoration of lost parts in animals 

 — how, in fact, are we to give an account of the 

 phenomena of reproduction by fission or gemmation, 

 in which mere isolated parts of an organism grow so 



