1896.] Variation after Birth. 23 



character has a habit of retreating into the germ where neither 

 they nor anyone else can find it. But this proposition is easy 

 enough of proof, viz., plants which start to all appearances per- 

 fectly equal, may be greatly modified by the conditions in 

 which they grow; the seedlings of these plants may show 

 these new features in few or many generations. Most of the 

 new varieties of garden plants, of which about a thousand are 

 introduced in North America each year, come about in just 

 this way. A simple experiment made in our greenhouses also 

 shows the truth of my proposition. Peas were grown under 

 known conditions from seeds in the same manner as the petu- 

 nias were, which I have mentioned. The plants varied widely. 

 Seeds of these plants were saved and all sown in one soil, and 

 the characters, somewhat diminished, appeared in the off- 

 spring. Seeds were again taken, and in the third generation 

 the acquired characters were still discernible. The full details 

 of this and similar experiments are waiting for separate publi- 

 cation. The whole philosophy of " selecting the best " for 

 seed, by means of which all domestic plants have been so 

 greatly ameliorated, rests upon the hereditability of these 

 characters which arise after birth ; and if the gardener did not 

 possess this power of causing like plants to vary and then of 

 perpetuating more or less completely the characters which he 

 secures, he would at once quit the business because there 

 would no longer be any reward for his efforts. Of course, the 

 Neol ►arwinians can say, upon the one hand, that all the vari- 

 ations which the gardener secures and keeps were potentially 

 present in the germ, but they cannot prove it, neither can they 

 make any gardener believe it; or, on the other hand, they can 

 say that the new characters have somehow impressed them- 

 selves upon the germ, a proposition to which the gardener will 

 not object because he does not care about the form of words so 

 long as he is not disputed in the facts. Weismann admit- that 

 " climatic and other external influences " are capable of affect- 

 ing the germ, or of producing " permanent variations," after 

 they have operated " uniformly for a long period," or for more 

 than one generation. Every annual plant dies at the end of 

 the season, therefore whatever effect the 



