86 THE GERM-PLASM THEORY 



so to speak. But granting this to be true we are 

 still confronted with the question : What makes 

 each of them live ? What sets agoing and keeps 

 agoing the processes, complicated and potent, of 

 which these little units are the theatre ? To this 

 question Weismann has a clear negative answer. 

 It is not a vital process of any kind. If one seeks 

 for a further explanation and asks why vital in- 

 fluences are out of court, it is true that one obtains 

 no very certain response. In the last analysis it 

 would seem to be argued that there is no such thing 

 as a vital force because it cannot be seen or demon- 

 strated, a form of argument which, if one agreed 

 with it, might be turned with considerable force 

 against the doctrine of the "vital units " itself, and 

 indeed against the whole of the germ-plasm theory. 

 But if there is no such thing as vital force, what 

 does this work ? Is it a chemical, or a physical, or 

 a chemicophysical operation ? It is quite clear 

 that no explanation of this kind will suffice. 



" Thus from all sides we are forced to the con- 

 clusion that the germ-substance on the whole 

 owes its marvellous power of development not 

 only to its chemico-physical constitution, whether 

 that be eminently simple or marvellously complex, 

 but to the fact that it consists of many and differ- 

 ent kinds of ' primary constituents ' (Anlagen), 

 that is groups of vital units equipped with the 

 forces of life, and capable of remaining latent in 

 a passive state, until they are affected by a liber- 

 ating stimulus and on this account able to inter- 

 pose successively in development." Vol. i. 402. 



