164 



OBSERVATIONS UPON MULING AMONG PLANTS. 



2. Again, it occasionally happens that where a plant cannot 

 be fertilized with its own pollen, that of another individual of 

 the same species, or even of some nearly allied species, is effi- 

 cient. Lobelia fulgens, for instance, though impregnable to its 

 own pollen, yields fruit with that of L. cardinalis and L. syphi- 

 litica, while the potency of the former pollen is proved by its 

 impregnating either of the latter species. Mr. Herbert found 

 similarly that Zephyr anthes carinata, though inactive to its own 

 pollen, was fecundated by that of Z. tubispatha. 



The effect of strange pollen on the female organs of the 

 matrix may be regard erl in four points of view — as causing dis- 

 organization, as imparting vital energy, as procreative, and as 

 giving form. 



1. The first action of the pollen is a certain degree of disor- 

 ganization of the stigma, and then of the blossom. This is the 

 consequence of every efficient impregnation. Imperfect im- 

 pregnation has also the same effect, but at a later period. 

 Blossoms which began to fade in ten or twelve hours after 

 natural impregnation, lasted more than eight days where the 

 dust of Lycopodium had been applied instead of pollen. Pollen 

 which will not fructify, sometimes however disorganizes the 

 stigmatic tissue, as is the case with Lychnis diurna dusted with 

 the pollen of Saponaria officinalis. 



The more powerful the action of the pollen, the sooner the 

 blossom fades. The contrary effect, however, is sometimes pro- 

 duced in absolutely sterile hybrids, such as Nicotiana paniculato- 

 Langsdorfii, in which the blossoms fall very speedily ; but when 

 the pollen either of the male or female parent is applied, they 

 last many days. 



2. In the instance just mentioned the pollen appears rather the 

 maintainer of life than the destroyer, though it has no quicken- 

 ing influence. In many cases the action of pollen, though not 

 sufficient to quicken the ovules, affects in different degrees the 

 outer envelopes of the seeds. 



3. The grand effect of fecundation is the formation of the 

 embryo. Without fecundation the capsule and external enve- 

 lopes of the seeds may indeed exist, but there can be no embryo. 

 Sometimes the influence of the male, sometimes that of the 

 female parent predominates. 



4. It remains, then, to consider the modifications of form pro- 

 duced by the pollen. In general, neither in form, size, nor 

 colour, is there any difference in the seeds of the matrix, what- 

 ever difference there may be in those of the male and female 

 parent. Variations in these points, indeed, do occur sometimes, 

 but rather morphologic phenomena than the effect of fecunda- 

 tion. In a very few instances, as in Dianthus superbus £ and 



