SYMBIOSIS 47 



can do it without having recourse to teleolog'ical explanation or 

 to "design" of a " prescient-from-all-eternity " order (to use 

 a term of Samuel Butler's). 



We may also incidentally admire the keen insight of that 

 great genius, Robert Chambers, the long unknown author of 

 the Vestiges of Creation (1844-53), who taught the principle 

 of " progressive development " years before Darwin, and 

 pointed to "the force of certain external conditions operating 

 upon the parturient system" as an important factor of 

 evolution. 



Experimental Morphology shows that on a small scale the 

 same, or similar, influence can clearly be seen to be operative. 

 Thus Goebel, Vochting, Knight, Klebs, etc., have shown that 

 if the primordia of a shoot are exposed to altered conditions of 

 nutrition at a sufficiently early stage, a complete substitution 

 of one organ for another is effected. The paramount influence 

 of nutrition in pre-determining form is thus again manifested. 



As regards the " summary exploitation " of the coloured 

 cells in Convoluta, we must remember that the plants here con- 

 cerned are primitive and short-lived. From the standpoint of 

 the species, as Prof. Keeble tells us, " the relation of certain 

 of its individuals with C. roscoffensis or C. paradoxa is an 

 episode without significance. . . . Of a swarm of flagel- 

 lated green cells, some small percentage meet the picturesque 

 fate of forming a tissue in the body of an animal. The others 

 pursue a less romantic adventure, either as green, self-support- 

 ing organisms or as colourless cells which batten on the offal 

 of the sea." 



By facilitating abstemiousness and sexual reproduction in 

 the Convoluta, the algal cells sacrificed are instrumental in 

 preventing the animal from lapsing into redundant and 

 degenerate forms of reproduction and becoming a pest similar 

 to the rose-aphis. They may thus be viewed as sacrificed 

 vicariously in order to prevent worse destructions, worse 

 calamities. 



