168 THE CASE AGAINST EVOLUTION 



pardoned a little impatience at such a travesty on science. 

 Again we have the appeal from realities to fancies, from the 

 seen to unseen. Moore sees no reason to doubt and is there- 

 fore quite sure that an unverified occurrence is taking place 

 "at a level of life lying deeper than anything the microscope 

 can reveal." The unknown is a veritable paradise for irre- 

 sponsible speculation and phantasy. It is well, however, 

 to keep one's feet on the terra firma of ascertained facts 

 and to make one's ignorance a motive for caution rather than 

 an incentive to reckless dogmatizing. 



To begin with, it is not to a single dispersed particle or 

 ultramicron that protoplasm has been likened, but to an emul- 

 sion, comprising both the dispersed particles and the dispersing 

 medium, or, in other words, to the colloidal system as a whole. 

 Moreover, even there the analogy is far from being perfect, and 

 is confined exclusively, as Wilson has pointed out, to a rough 

 similarity of structure and appearance. The colloidal system 

 is obviously a mere aggregate and not a natural unit like the 

 cell, and its dispersed particles (ultramicrons) do not mul- 

 tiply and perpetuate themselves by growth and division as do 

 the living components or formed bodies of the cell. As for 

 the single ultramicron or multimolecule of a colloidal solu- 

 tion, it may, indeed, be a natural unit, but it only resembles 

 the cell in the sense that, like the latter, it is a complex of 

 constituent molecules. Here, however, all resemblance 

 ceases; for the ultramicron does not display the typically 

 vital power of self-perpetuation by growth and division, which, 

 as we have seen, is characteristic not only of the cell as a whole, 

 but of its single components or organelles. Certainly, the dis- 

 tinctive phenomena of colloidal systems cannot be interpreted 

 as processes of multiplication. There is nothing suggestive of 

 this vital phenomenon in the reversal of phase, which is caused 

 by the addition of electrolytes to oil emulsions, or in gelation, 

 which is caused by a change of temperature in certain hydro- 

 philic colloids. Thus the addition of the salt of a bivalent 

 cation (e.g. CaCl? or BaClg) to an oil-in-water emulsion (if 



