366 Ever-sporting Varieties 



the old roots. Double tuberous begonias are or- 

 dinarily absolutely sterile throughout the sum- 

 mer, but towards autumn the new flowers be- 

 come less and less altered, producing some nor- 

 mal stamens and pistils among the majority of 

 metamorphosed organs. From these flowers the 

 seeds are saved. Sometimes similar flowers 

 occur at the beginning of the flowering-period. 

 Double garden-camomiles (Chrysanthemum in- 

 odorum plenissimum) and many other double 

 varieties of garden-plants among the great 

 family of the composites are very sensitive to 

 external agencies, and their flower-heads are 

 fuller the more favorable the external condi- 

 tions. Towards the autumn many of them pro- 

 duce fewer and fewer converted heads and often 

 only these are fertile and yield seeds. 



Ascidia afford another instance of this 

 periodicity, though ordinarily they are by far 

 too rare to show any regularity in their distri- 

 bution. However, it is easy to observe that on 

 lime-trees they prefer the lower parts of each 

 twig, while on magnolias the terminal leaves 

 of the branches are often pitcher-bearing. 

 Ascidia of the white clover have been found in 

 numbers, in my own experiment-garden, but 

 always exclusively in the spring. The thick- 

 leaved saxifrage (Saxifraga crassifolia) is 

 often very productive of ascidia, especially in 



