Morphology of the Citrus. 197 



the whole lot will be so different from both parents, as 

 to form the commencement of a new race. What gives 

 rise to these " breaks," as horticulturists call them, is 

 not sufficiently understood. Now as breaks do occur, 

 when plants are artificially crossed, so would they, I 

 think, be liable to occur, when naturally crossed, either 

 by insects or other ways. I have no means of knowing 

 just now whether seeds from the same plant, without 

 crossing give these decided breaks. The break or new 

 form can be, it would appear, of three kinds either a 

 reversion to some ancestral form, of which we may 

 know nothing ; or it may be an entirely new form ; or 

 a combination of both. All breaks cannot be reversions. 

 Supposing all the forms we see now have been brought 

 about by a series of breaks instead of by gradual 

 inheritance of accumulated variations, we must arrive 

 at a time when there was little or nothing to revert to. 



It is not improbable that, besides natural selection 

 by a gradual step by step process, natural breaks may 

 have played an important part in producing the infinite 

 forms we see in nature. Of course a break may be 

 either much more delicate or -much more robust than 

 either of its parents. In the first case, it would not 

 last long, unless it could occupy places untenanted by 

 other more suitable kinds. In the second case, it 

 would probably extinguish, and take the place of its 

 parents. Risso mentions several kinds of citrus raised 

 from seed in the South of Europe, which were hardier 

 than their parents, and which could therefore be pushed 

 further north without being injured by frost, and the 

 C. trifoliata is stated to withstand a cold climate better 

 than any other kind. 



There are so many varieties of cultivated citrus in 

 India, China, and the Malay archipelago, that it is not 

 improbable some may be descendants of the wild 



