THE SUPPOSED TRANSMISSION OF MUTILATIONS. 433 



shorter than 10-5 mm. Furthermore there was no difference in 

 this respect between the young- of the earlier and later generations. 



What do these experiments prpve ? Do they disprove once for 

 all the opinion that mutilations cannot be transmitted ? Certainly 

 not, when taken alone. If this conclusion were drawn from these 

 experiments alone and without considering- other facts, it might 

 be rightly objected that the number of generations had been far 

 too small. It might be urged that it was probable that the 

 hereditary effects of mutilation would only appear after a greater 

 number of generations had elapsed. They might not appear by 

 the fifth generation, but perhaps by the sixth, tenth, twentieth, or 

 hundredth generation. 



We cannot say much against this objection, for there are actual 

 phenomena of variation which must depend upon such a gradual 

 and at first imperceptible change in the germ-plasm, a change 

 which does not become visible in the descendants until after 

 the lapse of generations. The wild pansy does not change at 

 once when planted in garden soil : at first it remains apparently 

 unchanged, but sooner or later in the course of generations varia- 

 tions, chiefly in the colour and size of the flowers, begin to appear : 

 these are propagated by seed and are therefore the consequence of 

 variations in the germ. The fact that such variations never occur 

 in the first generation proves that they must be prepared for by a 

 gradual transformation of the germ-plasm. 



It is therefore possible to imagine that the modifying effects of 

 external influences upon the germ-plasm may be gradual and may 

 increase in the course of generations, so that visible changes in the 

 body (soma) are not produced until the effects have reached a certain 

 intensity. 



Thus no conclusive theoretical objections can be brought forward 

 against the supposition that the hereditary transmission of mutila- 

 tions requires (e.g.) 1000 generations before it can become visible. 

 We cannot estimate a priori the strength of the influences which 

 are capable of changing the germ-plasm, and experience alone can 

 teach us the number of generations through which they must act 

 before visible effects are produced. 



If therefore mutilations really act upon the germ-plasm as the 

 causes of variation, the possibility or even probability of the ultimate 

 appearance of hereditary effects could not be denied. 



Ff 



