THE ORIGIN OF VARIATIOXS .51 



ourselves with the adoption of vague but imposing 

 phrases, nor seek to darken counsel by words without 

 knowledge. 



In the case of the lowliest organisms, such as, 

 for example, the animal Ama'ba, or the vegetable 

 bacterium, we can draw no distinction between the 

 germ-plasm and the body-plasm. Any acquire- 

 ment, such as the exahation of virulence due to the 

 passage of disease -producing bacteria through the 

 body of a susceptible animal, must be a cause of 

 variation ; for the descendants of such bacteria are 

 certainly more virulent than were their ancestors 

 before their experience of this suitable environment. 



But the problem before us is the origin of varia- 

 tions in all the higher animals and plants, which 

 are propagated by bi-parental reproduction. 



In the first place, we find ourselves compelled to 

 reject certain suggested causes of variation in these 

 organisms. We find that, even assuming the acquire- 

 ments of the individual so to alter the germ-plasm 

 on occasion as to produce true variations, yet this 

 transmission of acquirements is totally inadequate 

 to explain the great majority of cases of variation. 



Even the most recent opinion of Weismann (which 

 is in some measure a concession to his critics), that 

 the germ-plasm, on rare occasions and to a small 

 extent, may be so affected by its surroundings as to 

 give rise to variations in the ofispring, is almost 

 infinitely far from being tantamount to au adequate 

 explanation of the cause of variations. 



We find, again, that it is impossible to explain 

 variation by the assumption of a direct action of the 

 external environment (by which clumsy phrase I 



