224 M. Ch. Nan din on Hyhridity in Plants. 



(2.) On the DiffevenGe, of the Fertility of Hybrids. 



Hybrids are self-fertile in all cases in which their anthers 

 contain well-organised pollen ; but if the quantity is very 

 small, it is well not to leave the impregnation to chance, 

 but to aid artificially in fertilising the hybrid with its own 

 pollen. I have done this in Luffa acutangulo-cylindrica of 

 the first generation, which has but few male flowers and a 

 small quantity of good pollen. 



In the majority of cases microscopic inspection sufiiciently 

 shows the character of the pollen ; the difi'erence in form, 

 size, and transparency distinguishes the good and bad ; and 

 it is easy to judge, at least approximatively, of the relative 

 quantity. Yet there are some cases, though not very 

 common, where this examination of the pollen is not suffi- 

 cient to determine whether it is active or inert ; for it may 

 happen that it has all the appearance of good pollen with- 

 out having its qualities. Such was that of Mirahih's longi- 

 Jloro-Jalapa, whose grains, although unequal, were not 

 deformed, and appeared full of fovilla, notwithstanding their 

 inefiicacy upon the stigmas of the two parent plants, as 

 well as upon those of the hybrid. Perhaps the employ- 

 ment of chemical reagents would better determine their 

 impotency. 



There are various degrees of fertility in hybrids by means 

 of pollen. We have seen Lvffa acutangulo-cylindrica of the 

 first generation extremely low in this respect, but in the 

 third remarkably productive. It is the same, and nearly to 

 the same degree, in Luffa amaro-cylindinca, Nicotiana rus- 

 tico-panictdata, dcn^ ijanicidaio-rustica, and in a great num- 

 ber of the toad-flax hybrids {Linaria purpureo-violacea) of 

 the second, third, fourth, and flfth generations. 



A greater richness of pollen is seen in Primid.a offcinali- 

 grandiflora, of the first, and especially second, generation, 

 and in Gucumis Meloni-trigonus, &c. In fine, there are some 

 hybrids where the pollen is little inferior, if at all, in per- 

 fection to the most legitimate species. This is the case 

 in Coccinia Schimpero-indica, Datura metehido-Metel, D. 

 Stranionio-Metel, D, Stramonio-lcevis, Nicotiana angustifolio- 

 ')nacroj)hylla, N. texano-rustica, N. persico-Langsdorffii, Pe- 



