26o SCIENCE PROGRESS 



But, whilst domestication is thus justly suspect, we have 

 in Symbiosis a far better principle of progressive modification. 

 Symbiosis is not only free from the blemishes of domestication, 

 but represents also the source of all wholesome accumulation 

 of what I call physiological capital, which is essential to the 

 progress of organic life. Symbiosis implies work and systematic 

 service of organism by organism by the method of " part- 

 nership." 



Ability to rely upon duly " remunerated " biological 

 partners makes possible a progressive avoidance of waste and 

 of loss of energy. The symbiotic relation proved of such avail 

 in health and in progress that a steady expansion of its range 

 could take place. The partners betook themselves to ever 

 wider fields of action, and, in lieu of the primitive " attached " 

 forms of Symbiosis, wider and more evolved forms of " non- 

 attached " Symbiosis became established, until whole groups 

 of organisms came to be symbiotic with others. Partnership 

 is by no means confined to physical attachment, and it is to 

 the partnership, the sociological aspect of the relation, rather 

 than to the narrow morphological aspect, that I wish to call 

 attention. 



To take a concrete, though primitive, case of Symbiosis 

 as discovered and communicated by Mme van Bosse in her 

 work on tropical algae : In some cases of alga-cum-sponge 

 Symbiosis the alga branches profusely and ramifies through the 

 canal system of the sponge, the alga using for food the carbon 

 dioxide given off by the living sponge tissues, obtaining its 

 salts from the water passing through the canals, and, on the 

 other hand, supplying the sponge with the oxygen given off 

 in photosynthesis. 



What emerges is this : the sponge needs a particular 

 substance, which the alga knows how to manufacture, and which 

 the latter can well afford to surrender in exchange for a spare 

 product of the sponge. Given a situation such as this — given, in 

 other words, a pair of opposites to be adequately accommodated, 

 given also sufficient disposition on the part of the opposite 

 parties, the opportunity is provided for a continuous process 

 of mutual stimulation, purporting increased mutual benefits 

 and conducing in the result to increased specialisation, increasing 

 capacity and efficiency, and increasing yields, not only to the 

 " partners," but also to life generally, which is thus the richer 

 for the adoption of the symbiotic mode of life, wherever met 

 with. 



The exchange of substances between alga and sponge is, 

 of course, but an example of the complemental relation existing 

 between plant and animal on the grand scale of nature. But, 

 inasmuch as this complemental relation is as indispensable as 



