SYMBIOSIS 33 



form may not have much significance, but there are others 

 which are of more importance. " The plantagen, like the cater- 

 pillar, goes to sleep at the approach of winter, and in the 

 flower-bud, as in the chrysalis, are provided the essentials for 

 carrying on the race. In both cases, as soon as the winter's 

 sleep is over, the final change comes swiftly from the bud 

 issues the flower and from the chrysalis the butterfly, the 

 latter with its eggs to start the cycle afresh and the former 

 with its seeds." 



Mr. Davidson suggests that it would be unreasonable to 

 ascribe these two series of extraordinary events to coincidence. 

 " They must be similar effects produced by similar causes." 

 Nor is the reason for the similarity far to seek when we find, 

 as presently we are reminded, that ultimately the phenomenon 

 is related with nutrition. 



If a caterpillar is supplied with an abundance of suitable food and 

 kept at a suitable temperature, it will not enter the chrysalis stage 

 until long after its usual time, as, indeed, naturally happens in the 

 case of certain wood-boring caterpillars which, surrounded by food and 

 protected by its means from great variations of temperature, undergo 

 no metamorphosis for at least two years ; and if a tree is grown under 

 similar conditions, the buds which it bears do not enter the stage which 

 results in flowers they merely increase in number. That is, the tree 

 keeps on growing. 



That a surfeit of food is apt to impede progressive sexual 

 developments in both plant and animal is a fact I have been 

 urging in all my writings. The above passage requires an 

 addendum concerning this factor of surfeit, viz., that it 

 amounts to a temptation of both plantagens and lowly animal 

 types to slacken in symbiotic activity. Nutrition, in view of 

 the fundamental fact of symbiosis, has an essentially 

 remunerative aspect the recompense for proper nutritional 

 habits consisting in favourable bio-economic, favourable bio- 

 chemical, and related physiological circumstances, as instanced 

 by the existence and adequacy of " love-foods." 



As soon as an organism becomes surfeited it is apt to lose 

 its erstwhile internal (physiological) co-operativeness pari 



