THE GERM-PLASM 39 



loo-ical units, which are themselves composed of molecules, or, ' 

 as Briicke first expressed it. protoplasm is ^organised / As I 

 have shown in the historical introduction to this book. Herbert 

 Spencer, and more recently de Vries and Wiesner, have assumed 

 the existence of such organic units. -^ 



De Vries, moreover, points out tha_t protoplasm possesses 

 certain -historical ' properties besides its physical and chemical 

 ones.^irmay certainly be doubted, as de \'ries states, whether 

 it wiU ever be possible to produce ' living protoplasm otherwise 

 than in a phylogenetic manner.' that is to say, to make it artili- 

 cially in the laboratory; but it cannot be admitted that this 

 is so improbable, merely because the conception of protoplasm 

 demands that it should be derived from pre-existing protoplasm. 

 This would exclude for ever not only the possibility of its pro- 

 duction in our laboratories, but also its logically inevitable 

 and indispensable primary formation in the great laboratory of 

 Nature. Most, in fact probably all, kinds of protoplasm with 

 which we are acquainted possess historical qualities, not z« 

 addition to, but within their physico-chemical ones; that is, 

 they contain special modifications of construction peculiar to 

 themselves which arose in adaptation to the conditions of life^ I 

 and have been transmitted for a long period of time. But pro- 

 toplasm which does not yet possess -historical" i.e., inherited 

 qualities, does not seem to me to be inconceivable. It would 

 be the simplest form of living matter which, in virtue of its 

 constitution, possessed the primary vital forces, — assimilation, 

 metabolism, and so on. The historical qualities of the proto- 

 plasm, its special hereditar}' tendencies, are not connected with 

 these primary vital forces. The latter must exist independently 

 in all protoplasm. 



All those writers * who have assumed the existence of units 

 on which the vital forces of protoplasm depend, have pointed 

 out that they are not chemical molecules, for the latter do not 

 possess the power of assimilation and reproduction. Hence it 

 follows that protoplasm is a complex substance which is not 

 homogeneous, but which consists of different kinds of molecules. 

 There is therefore no m.olecule of protoplasm, but we have to 

 imagine that even in its simplest modifications, protoplasm 

 invariably consists of groups of molecules, each of which is 



* Briicke, Herbert Spencer, de Vries, and Wissner. 



