INTRODUCTION TO CRYPTOGAMIC BOTANY. 51 



artificially, it is conceivable that the pollen tube may, in 

 certain cases, penetrate, or, at least, come in contact with the 

 embryo-sac, quite as easily as by means of a stigmatic tissue. 

 Dr. Hooker has lately made some experiments of cutting off 

 the stigmatic rays of unimpregnated poppies, and yet has 

 obtained perfect seeds.* It is alleged that direct impreg- 

 nation is a sign of inferiority, resembling as it does what takes 

 place in many reptiles. But the whole matter of impregnation 

 is so very different in animals from the correspondent process 

 in the higher plants, that no weight can be attached to such a 

 resemblance. Cr3rptogams might be considered of superior dig- 

 nity to Phajnogams, for example, because of their spermatozoids. 

 The result of impregnation in the case of lizards is, in many 

 respects, far inferior to animals produced from more normal 

 impregnation. But as much cannot be said of Conifers, nor 

 do I think them at all degraded, because impregnation does 

 not take place without the intervention of a stigmatic tissue. 

 In many reptiles, impregnation is as precarious as in trees 

 with distinct sexes, the water in the one case being the vehicle, 

 in the other the air. Besides, in GnetuTii and Ephedra there 

 is an organ developed which performs the functions of a stigma, 

 though not arising from the placenta ;t but even supposing it 

 to be wholly inoperative, it is at least representative, like the 

 mammae on the breasts of male quadrupeds, which do oc- 

 casionally contain milk as in the female. It is not, indeed, 

 quite clear whether the simpler mode, judging by analogy, 

 may not be of the higher dignity. No one would pretend 

 that in those cases where the impregnating substance is stored 



* Hooker iu Gardener'' s Chronicle, 1855. 



t Much, of course, depends upon the fact, whether impregnation is 

 effected before the formation of the envelope, which bears the pseudo- 

 stigma. The argument would be stronger if the older views of the 

 structure of the flower were coi-rect, which, on examination, appears to 

 be the case ; the envelope in question is external to the nucleus, and 

 therefore the processes cannot be the same with the curious bodies 

 which occur in Thuya, In Larix the stigmatic cells, as figured by 

 Geleznoff, Ann. d. Sc. Nat., Ser. 3. vol. xiv. tab. 13, fig. 15, 16, whose 

 paper may be consulted respecting the peculiarities of the pollen in 

 Conifers, are equally indei)endent of the placenta. 

 4 * 



