Cha". VIII. of the crossed TLANTS. 289 



grew in pots in the hothouse; but this may be 

 attributed to the self-fertilised plants being more 

 tender, so that they suffered more than the crossed 

 when both lots were exposed to a cold and wet summer, 

 Lastly, with one out of two series of Reseda odorata. 

 grown out of doors in rows, as well as with Beta 

 vulgaris, the crossed plants did not at all exceed the self- 

 fertilised in height, or exceeded them by a mere trifle. 



The innate power of the crossed plants to resist 

 unfavourable conditions far better than did the self- 

 fertilised plants, was shown on two occasions in a 

 curious manner, namely, with Iberis and in the third 

 generation of Petunia, by the great superiority in 

 height of the crossed over the self-fertilised seedlings, 

 when both sets were grown under extremely unfavourable 

 conditions; whereas owing to special circumstances 

 exactly the reverse occurred with the plants raised from 

 the same seeds and grown in pairs in pots. A nearly 

 analogous case was observed on two other occasions 

 with plants of the first generation of Nicotiana. 



The crossed plants always withstood the injurious 

 effects of being suddenly removed into the open air 

 after having been kept in the greenhouse better than 

 did the self-fertilised. On several occasions they also 

 resisted much better cold and intemperate weather. 

 This was manifestly the case with some crossed and 

 self-fertilised plants of Ipomoea, which were suddenly 

 moved from the hothouse to the coldest part of a cool 

 greenhouse. The offspring of plants of the eighth 

 self-fertilised generation of Mimulus crossed by a fresh 

 stock, survived a frost which killed every single self- 

 iertilised and intercrossed plant of the same old stock. 

 Nearly the same result followed with some crossed and 

 self-fertilised plants of Viola tricolor. Even the tips 

 of the shoots of the crossed plants (f Sarothamnus 



u 



