EEV. G. HE Jf SLOW FERTILISATION' OF PLAJ^TS. 205 



although you cannot generalise fi'om these effects, yet they occurred 

 in individual cases, where the crossed plants showed some special 

 or particular advantage in other respects than height, weight, and 

 fertility ; for example, on one occasion he planted the self -fertilised 

 some hours, or even a day or two before the others, and then the 

 crossed overtook them and beat them in the race. Then he found 

 they were better able to resist unfavourable conditions of various 

 kinds : such as a sudden removal from the greenhouse to the open 

 ground, which checked the self-fertilised, whereas the others were 

 able to stand it. But this was only in particular instances. They 

 also better withstood cold and intemperate weather, and a severe frost 

 on one occasion. The period of flowering of the intercrossed was 

 earlier than that of the self-fertilised, sometimes days, or even, as in 

 the case of Cyclamen., three weeks. To sum up the results, we find 

 that the experiments establish these main facts. By introducing 

 a new stock, the cross benefits the plants in every way, they grow 

 higher, their leaves are larger and greener, and they become alto- 

 gether finer and more bushy plants, and produce a greater pro- 

 fusion of flowers, while the flowers are subject to greater 

 variations of colour. Secondly, by intercrossing two plants of the 

 same stock, you get a certain amount of benefit, but in a lesser 

 degree ; but if one continues to cultivate the same stock year after 

 year, the benefit derived at first gradually disappears, the plants 

 finally become as if they fertilised themselves, and the flowers 

 retain the same uniform colour. 



Then we come to the process of self- fertilisation. We have 

 considered the three kinds : a distinct cross, i.e. with different 

 stock ; crossing the same stock ; and crossing flowers on the same 

 plant ; but self-fertilisation is the subject on which I join issue with 

 Mr. Darwin. Throughout the book he uses the phrases "evil 

 effects of," and "injurious effects of," in regard to self -fertilisa- 

 tion. Of course he has proved the benefits of crossing ; but to say 

 that the opposite process is "injurious" is, I think, misleading. For 

 when you read of "injurious effects" you infer some unhealthiness 

 or infertility. Cases amongst cultivated plants may occur where 

 something like "injurious effects" may be recognised, but apart 

 from individual and exceptional cases, to lay it down as a broad 

 general rule is, I think, erroneous. Mr. Darwin heads a section on 

 p. 303 as follows : — " On the preservation of the good effects from 

 a cross and the evil effects from self -fertilisation." But out of the 

 seventy-four cases he has cultivated, he has only got three plants to 

 bring forward. The first one, Nemophlla iusignis, must be struck 

 out altogether, because he says : " This experiment was quite 

 worthless." That reduces us to two cases only. One is the 

 common pansy, and the way in which he wished to show the 

 benefit was by taking two plants cultivated for one generation ; 

 the one crossed, the other self-fertilised, and the ratio of the two 

 was as 100 to 42, showing a very great benefit to the intercrossed. 

 He now crossed the seedlings of both of these two ; and he thought 

 the one doubly-crossed would show the transmitted benefit and be 



