THE VEGETABLE CELL. 125 



Ferns, observed the penetration of the spiral filaments into the 

 canal just referred to. His idea that he saw the lower part of 

 a spiral filament become transformed into the embryo, is doubtless 

 the result of a mistake, readily to be pardoned in such difficult 

 investigations, which does not damage the discovery we owe to 

 him. There can be no doubt that in the rest of the plants under 

 consideration, the spiral filaments are the bearers of the impreg- 

 nating substance, since in the Rhizocarpeee, the spores which are 

 allowed to germinate separately fi-om the small spores producing 

 the spiral filaments, are capable indeed of forming a pro-embryo, 

 but not of producing a plant fi:om the ovules of this. 



The plant, which is developed in the lower cell of the ovule, is 

 organically connected with the pro-embryo ; it is a bud growing 

 up from it, so that the leafy stem thence produced has no primary 

 descending axis. (An error ; see p. 137 — ^A. H.) 



According to Hofmeister's researches, the relation of the anthe- 

 ridia of the Mosses to the rest of the plant is again different. It 

 has long been known, as already mentioned, that the rudiment of 

 the fruit of these plants remains undeveloped when no antheridia 

 are produced. This is explained by Hofiieister's investigations ; 

 according to these, the rudiment of the fi:uit of tlie Moss (the 

 so-called archegonimn) greatly resembles the ovules of the 

 Ferns, since underneath the so-called style, lies a large cell, which 

 by subdivision is converted into a cellular body, growing down- 

 wards and becoming blended with tlie stem at the one end, and 

 becoming prolonged upwards, and developed into the sporangium 

 at the other. So that while in the Ferns, &c., the spore only 

 forms the pro-embryo without impregnation, and the impregnation 

 is necessary for the development of a leaf-bud, which grows up 

 into the leafy stem forming the sporangia, the spore of the Mosses 

 forms the pro-embryo and the leafy stem without impregnation, and 

 this operation only causes the development of the spore-producing 

 pa^-t of the plant (see W. Hofineister, ^'uh d. FruchtbilcL unci 

 Keimung d. hoh. Kryptog" — Bot Zeit 1849, 793; Mettenius, 

 ''Beitr, z. BoV 1. (Also "EoimeisteVy'^FTUGhtbildung, Keimung, <&g., 

 der Gryptogamen" 4ito, Leipzig, 1851; and Henfrey^'s Report in 

 the Transactions of the British Association, 1851; and Memoir 

 on the '^Beproduction of the Higher Cryptogamia/' &c. — ^'Ann. of 

 Nat History,'' sec. 2. vol. ix., 1852 — ^A. H.) 



5. PBOPAGATION" BY SEEDS. 



Proceeding to the theory of the impregnation and the formation 

 of the embrj-oin the Phanerogamia, we arrive upon ground which 

 has been levelled by the researches of the last ten years. In no 

 part of our science has careful investigation, penetrating with un- 

 tiring patience into ultimate details, yielded more brilliant results, 

 yet in no other part have the hardly-earned facts been so violently 

 opposed, the conclusions, safely established, being even still contin- 

 ually called in questiou onthe strength of superficial investigations. 



