ySa LECTURE XLIV. 



own pollen, in this case the pollen of the other kind may exclude that of its own kind 

 from the fertilisation. If various kinds of pollen come on to a stigma at different 

 times, and if the later coiner is of greater sexual affinity, it can only then be still 

 effectual in fertilisation if that which first entered has not yet effected fertilisation, or 

 injury; in Nicotiana hybridisation can no longer be prevented by its own pollen 

 after two hours, in Malva and Hibiscus after three hours, and in Dianthus after five 

 or six hours. 



(6) The hybrid stands, according to its systematic characters, somewhere between 

 the different ancestral forms. For the most part it maintains the medium; more 

 rarely it resembles one of the two parent forms more than the other, this being more con- 

 spicuous in the case of hybrids between varieties than with . those between species. 

 Hence it follows that in the case of reciprocal hybrids of species A and B, the hybrid 

 ^ 5 is in general externally similar to the hybrid B A. Nevertheless both may ex- 

 hibit certain internal differences. Thus, according to Gartner, the hybrid Nicotiana. 

 paniculalo-rustica is more fertile than the reciprocal hybrid N. rustico-paniculata. An 

 internal difference between reciprocal hybrids also expresses itself in that the one is 

 more variable than the other ; thus, according to Gartner, the progeny of Digitalis 

 purpureo-lutea are more variable than those of D. luteo-purpurea, and those of Dian- 

 thus pulchello-arenarius more variable than those of D. arenario-pulchellus. 



When two species A and B form hybrids, and the one species A exerts a greater 

 influence on the form and properties of the hybrid than the other Species B, the hybrid; 

 when it and its descendants are fertilised by A, must be transferred into the parent- 

 form A more rapidly than it passes over into the parent-form B by fertilisation with 

 B. Thus, according to Gartner, the hybrid of Dianthus chinensis and D. caryophyllm, 

 when repeatedly fertilised by the latter, was transferred into D. caryophyllus after three 

 or four generations, whereas fertilisation with D. chinensis yielded descendants of the 

 form of D. chinensis only after five or six generations. 



(7) The characters of the parent-forms are as a rule transmitted to the hybrid 

 in such a way that in each character the influence of both parents is evident: a mutual 

 fusion of the various characters occurs. In the case of species-hybrids this is more 

 decidedly expressed than with hybrids between varieties. In the latter certain un- 

 essential characters of the ancestors occasionally occur separated next one another ; 

 for instance, various kinds of streaks and spots instead of a corresponding mixture of 

 colours. A hybrid which Sageret derived from Cucumis Chate (female) with C Melo 

 Cantalupus (which possessed a reticulate peel) produced fruit with yellow flesh, 

 reticulate markings on the peel, and fairly strong ribs like the father, but white seeds 

 and sour taste like the mother; another hybrid of these two species had on the 

 contrary fruit with sweet taste and yellow flesh, like the father, but white seeds 

 and 'smooth peel, like the mother. To this category belongs also the hybrid 

 between Cytisus Laburnum and C. purpureus, the branches of which resemble, wholly 

 or in part, sometimes the one, sometimes the other parent-form. I found what was 

 very probably a hybrid of Antirrhinum majus, the inflorescence of which bore on the 

 one side of the axis only uniformly dark red, on the other side yellow flowers ; between 

 the two halves of the inflorescence stood one flower which was coloured half red and 

 half yellow. 



(8) Besides the inherited peculiarities, the hybrid usually possesses new characters 



