0B3EKVATI0NS UPON MULING AMONG m.ANTS. 5 



the male, in animals, giving origin to internal qualities, the 

 female to external ; to another, the former to the cellular system, 

 the latter to the nervous, &c. Amongst plants, the difference 

 of opinion is as great ; but the truth appears to be, tliat no ge- 

 neral rule can be laid down — in Digitalis the influence of the 

 female parent being predominant, in Nicotiana that of the 

 male, and the differences exhibited by individual species are no 

 less decisive against any universal law. And this is no less true 

 as to comparative degrees of fruitfulness. Indeed, the identity 

 of the produce, when the sexes are reversed, is a sufficient proof 

 of its non-existence. 



In the occurrence of exceptional types it is probable that the 

 difference arises from some peculiar constitution of the individual 

 ovule, rather than from any different condition of the pollen. 



It is curious that tiie specific difference of nearly allied species 

 appears more distinct in the hybrids to which they give rise 

 than in the pure species. For instance, Lobelia cardinalis^ 

 fulgens, and sple?ide?is, than which no species can well be more 

 intimately allied, give totally distinct hybrids when united with 

 £>. syphilitica ; and many other instances might be brought for- 

 ward : while on the contrary Nicotiana magnifolia, Diacrophylla, 

 marylandica, and petiolata give identical hybrids when impreg- 

 nated with N. glutinosa. The obvious conclusion is, that tlie 

 supposed species are in reality mere forms, and that hybrid types 

 depend entirely on the specific distinction of species, and not on 

 any external influences. If such were the case, exceptional 

 types would be of more common occurrence. 



One of the most singular effects of hybridization is that which 

 is sometimes produced on tiie cotyledons of the mule in the first 

 generation. It often happens that in a given genus there is 

 a strong general resemblance in the form of the cotyledons. But 

 this is not always the case. In Dianthus they vary consider- 

 ably, and there is a corresponding variation in the hybrids, as is 

 also the case with Nicotiana qtiadrivalvis, in which the cotyle- 

 dons differ greatly from those of other species. 



The general type of a hybrid is preserved throughout the 

 whole life of an individual. Mr. Herbert found this to be the 

 case in hybrids of Camellia. The blossoms, however, do not 

 always remain so constant, especially in hybrid varieties, as the 

 florist knows to his cost. 



Different degrees of resemblance to the parent types are ex.- 

 hibited by different hybrids, insomuch that though, as Mr, 

 Herbert says, a well-skilled florist may guess the result of any 

 particular experiment with tolerable accuracy, yet as the forms 

 are not fashioned according to strictly mathematical laws, but 

 after some vital energy which we can only estimate by its effects, 

 we can form no absolutely certain anticipation. 



