THE LIVING SUBSTANCE. 1 47 



Stance. Such parasitism as does not belong with phenomena 

 of true fosterhood may arise in varied ways. It may occur 

 either as direct selection of another animal as a chosen source 

 of supply, or accidentally from ingestion of one organism by 

 another. The organism so ingested may find its new sur- 

 roundings so much to its purposes, that is, so much in accord 

 with established substance habits and organs of its own, that, 

 far from succumbing and becoming chemically disintegrated, it 

 is as it were enclosed in a factory or source of artificial supply. 

 Instead of serving as food for its captor, it uses the latter 

 either as endosarc, or purveyor organ, or actually and directly 

 as living food — devouring its tissues. Or, it may pass to 

 some special area and there merely filch from the prepared or 

 selected food what its own uses require. It is not strange 

 that under such circumstances the plastic substance should lay 

 aside or modify substance organs for securing and preparing 

 its food, while retaining and accentuating those which best fit 

 in with its new set of opportunities and compulsions. In a 

 retention of their own individuality by grafts or transplanted 

 structures, one sees that part of an organism may continue 

 to maintain its selfhood while fed by another organism, of 

 which by substance parasitism it becomes physically an inte- 

 gral part. // shows again the importance of the substance as 

 such, and that the local form is not merely part of a whole 

 organis7n as such, but primarily and radically an expression of 

 substance habit. (See Heredity.) Such facts throw light also 

 upon the physiological differentiation of substance organs with 

 continuity of a physical and physiological nature between 

 them. 



[145] Once established as dependent, the parasitic sub- 

 stance, whatever its habit, forces the supporting substance or 

 organism to play the part of foster parent and itself resumes a 

 role which as fosterling substance, or perpetuation area, it 

 once played. For among all the multiplex dependent areas, 

 those most unmitigatedly parasitic and exacting are the per- 

 petuation or offspring areas. By a parasitism which is in 

 harmony with its fundamental structures and habit, or which 

 releases it temporarily from great enforced strain of its condi- 



