THE LIVING SUBSTANCE. 163 



a purposive habit controlled by the organism. By changing 

 this standpoint, — by taking structure and functions of vesicular 

 organs in their relation to the substance as such and to each 

 other as organs of this, — much will be gained. In any visi- 

 ble structure the continuous substance is a protoplasmic foam. 

 From or through this must the coarser vesicular inclusions be 

 built up and maintained, either chemically in situ by the local 

 substance, or as deposited products of the general substance, 

 brought, it may be, from some distance by physical or physio- 

 logical agency; they may also be caused by aggregation of 

 minuter vesicles, or by their bursting into each other ; or by 

 protoplastic activities. Except where formed by direct proto- 

 plastic ingestion, they are modifications of existing minuter 

 inclusions; in all cases they are due to functions of the finer 

 foam. Being products of a more primary set of structures 

 and functions they are secondary in origin and may be purely 

 incidental to the more intimate and basic life history and 

 habit of the continuous substance. 



Once formed, each new series of vesicular inclusions neces- 

 sarily introduces new interactions and new interrelations, 

 chemical, physical and physiological. These can create for 

 the mass such functional possibilities as may materially alter 

 its habits as organism. For instance, while the finer foam 

 carries what can for relatively short periods maintain its func- 

 tional activities, a fluid structure of Biitschli whose inclusions 

 are of reserve similar material, can make the general or local 

 substance independent of renewed appeal to external environ- 

 ment for much longer periods. Such a structure by receiving 

 excretions as well as excess of specific nutriment or stimulus 

 can also prevent clogging, or impeding, or functional waste, of 

 the active substance, and can save loss of time, force and sub- 

 stance in deportation by interalveolar currents. It is a con- 

 server of established habits as well as an initiator of a new 

 series of functional relations. It offers increased leverage, and 

 opportunity for organization of contractile powers on such a 

 scale as can more patently alter shape or displace a mass or 

 area. It keeps together relatively large quantities of sub- 

 stances secreted or excreted by the general substance or pro- 



