650 LECTURE XXIII. 



similarly, the hereditary characters of the oophore are trans- 

 mitted through the sporophore to the succeeding oophore 

 We will in our further discussion of Heredity, as far as 

 concerns plants with alternation of generations, regard two 

 successive sporophores or oophores as standing to each other 

 in the relation of parent and offspring. 



With regard, next, to individuals developed from sexually 

 produced spores, we would naturally expect that they 

 should present a combination of the characteristics of the 

 two parents ; and this they actually do in various degrees. 

 Darwin has pointed out that when two individuals, belonging 

 to the same family, but distinct enough to be recognised, 

 or two well-marked varieties, or two species, are crossed, 

 the usual result is that the immediate offspring are inter- 

 mediate between their parents, or resemble one parent in 

 one part and the other in another part. But this is by no 

 means an invariable rule ; for in many cases the characters 

 of the one parent are much more marked in the offspring 

 than those of the other ; that one parent is prepotent over 

 the other. In illustration of such a result from the crossing 

 of varieties, Darwin mentions the following examples. Plants 

 with striped flowers when crossed with others of the same 

 species having uniformly coloured flowers give rise to seed- 

 lings which have uniformly coloured flowers. Again, when 

 a plant of Snapdragon (Antirrhinum majus) with peloric 

 flowers was crossed with pollen from a flower of the common 

 form, and the latter, reciprocally, with pollen from the peloric 

 form, none of the seedlings had peloric flowers, a result which 

 was also obtained by Naudin with a peloric Linaria. 



The relation between the parents is still more strikingly 

 shewn in the case of hybrids. In many cases when species 

 are crossed, the hybrid produced is the same whether A has 

 been fertilised by pollen from B, or B by A ; in other words, 

 the hybrid BA is precisely similar to the reciprocal hybrid 

 AB. In such cases the influence of the reproductive cells is 

 clearly equal. In some cases, however, the hybrid resembles 

 the one parent more than the other ; so that the hybrid B A is 

 not quite similar to the hybrid AB. There is a ready method 



