444 NOTES AND MEMOEANDA. 



Nutrition of Phanerogamic Parasites. — M. Chatin forwards to 

 the Frcucli Academy * the result of some investigations on the mode 

 in which parasitic flowering plants derive their nutriment from the 

 host. This is effected by means of a kind of conical pivot or peg, 

 performing the double functions of an ordinary root, viz. to fix the 

 plant, and to absorb nutriment. The extremity of this cone, although 

 consisting entirely of parenchymatous tissue, has a remarkable power 

 of forcing itself through the tissue of the host, even when this is of 

 very great hardness. In certain cases, and especially in the mistletoe, 

 lateral suckers are formed, in addition to the terminal one. The 

 structure is the same in all important points whether the parasite 

 obtains its nourishment from the root of the host, as in the case of 

 Thesium and Pedicularis, or from the stem, as in Cuscuta, Cassytha, 

 and Viscum. 



Polyembryony, true and false, and its relation to Partheno- 

 genesis. — Professor Strasburger's researches f upon the fecundation of 

 the angiospermous Phanerogams show that the embryo-sac very seldom 

 produces more than one embryonal vesicle which is fecundated or 

 cajjable of being fecundated. The single constant excepticm to this rule 

 known to him is that of Santalum album, which produces two, besides 

 one or two orchids in which the embryonal vesicle occasionally 

 divides into two. True polyembryony must therefore be very rare in 

 Angiosperms. But seeds containing more than one embryo are of 

 common occurrence in the orange, Funhia, Allium, Nuthoscordum, 

 &c. According to Strasburger, all supernumerary embryos in such 

 cases are adventitious, originate outside the embryo-sac, by a kind 

 of prolification in the nucleus, and are not fecundated at all. They 

 appear in the form of minute cellular protuberances, which lengthen 

 by degrees and push into the embryo-sac by a sort of hernia, or pierce 

 their way into it, becoming in the ripe seed veritable embryos, which 

 it is not easy to distinguish from the one resulting from the fecunda- 

 tion of the embryonal vesicle itself. Independent as these adventitious 

 embryos are of fecundation, yet Strasburger could not obtain them in 

 Nothoscordum when he had removed the stamens before flowering, 

 and prevented access of pollen. But it appears that Ccdehogijne is a 

 case of this kind, namely, one in which an adventitious embryo is 

 habitually produced, instead of the normal embryo, which fails from 

 the want of fecundation, the male plant not being in cultivation. It 

 is stated that this is not a mere inference, but that Strasburger has 

 traced the development of the embryonal vesicle in the ovule of 

 Ccclebofjync, followed by its disappearance and resorption, and by the 

 independent production of adventitious embryos in the manner above 

 described. 



This, then, gives an explanation of the long-disputed partheno- 

 genesis of Ccelehogyne, and therefore of the less notable instances. 



Parthenogenesis, it is then concluded, is only so in appearance ; it 

 is sometimes, and perhaps in all cases, " a prolification of the nucleus." 



* 'Comptes Rendus,' Ixxxviii. (187i)) 108. 

 t ' Jen. ZeitscLr. f. Nat.,' v. (1878) (Ji7. 



