THE VEGETABLE CELL. 139 



tlio secondary embiyo-sac&, grow oaward in the cellular tissue Ijing in a 

 cavity of the primary embryo-sac, and push the embryo out of the secon- 

 dary embryo-sac. In this way are formed as many embryos as there are 

 secondary embryo-sacs ; but the four or five cells forming the thread-like 

 suspensor may separate from each other, and every one form a special 

 embryo. The embryo itself, moreover, exhibits a peculiar growth, for 

 while its cotyledonary end is composed of a connected, well-defined mass 

 of cells, its radical extremity is formed of a loose mass of cellular tissue, 

 which grows back on the suspensor, its cells only becoming more com- 

 pactly conjoined at a later period. Finally, in Thmja^ a whole mass of such 

 suspensors are formed, which terminate in an embryo below, side by side, 

 in one embryo-sac. The numerous embryos originating in one ovule seem 

 all to be equally capable of living, and are developed up to a certain point, 

 bat then, from some unknown cause, all die away except one. (Robert 

 Brown, " On the Flurality and Development of JEnihryos in tJie Seeds of 

 tlie GonifercB',' — Ann. Wat Hist, 1. 8er. xiii. 368 ; Mirbel and Spach, 

 '' JVotes sur rEjiihryogenie dw Finns Zarido" &)o./' Ann. des Sc. nat^ 

 2 S6r. XX. 257 ; Pineau, " Sur la Formation de VEmbryon chez les Goni- 

 fere^l' — Ann. des Sc. nat 3 Ser. xi. 83 ; G^leznojBT, "/Swr rUmhryogenie du 

 Meleze, Bulletin^ de la Societe deNatwral. de Moscou^' xxii, '^ Ann. des So. 

 naf" 3 S"er. xiv.)^ 



Observ. 3. If Schleiden's theory of impregnation had proved true, it 

 would have farnished incontestibie proof that no embryo can originate in 

 the ovule without application of pollen to the stigma. With the con- 

 firmation of the earher view of the import of the pollen-grain, the doubt 

 again arises whether the geminal vesicle is not in isolated cases capable of 

 development into an embryo without impregnation. Improbable as such 

 an exception seems, when we look at the thousands of experiments which 

 declare the necessity of impregnation, the absolute impossibility of it can 

 the less be proved that undoubted cases of the possibility have been 

 shewn in the Animal Kingdom. The greater the accuracy in the observa- 

 tions, indeed, the more clear it became that the cases in which it was 

 supposed that the development of fertile seeds without impregnation had 

 been obseiwed, in the hemp, spinach, <fec., arose from mistakes, but certain 

 cases still remain in which the problem has not yet been solved. In 

 reference to this, mention must particularly be made of the Euphorbia- 

 ceous plant, Ccelohogyne 'iZ-ici/o to, described by John Smith (^^Linn. Trams.^'' 

 xvhi. 510), in which not a trace of anthers could be found, either by 

 Smith, or by Francis Bauer, Lindley, and others, and yet it bore perfect 

 seeds, Gasparrini likewise asserts {^^Ann. d. So. nat^^ 3 S^r. v. 206) that 

 the figs developed in summer never contain male flowers, and yet produce 

 seeds which contain an embryo. 



c. THE CELL AS AF ORGAJST OF MOTIOH. 



AltlioTigh plants in general appear completely fixed and motion- 

 less, a close examination leads to the detection of movements of 



^ Hofmeister has recently shewn that great analogy exists between 

 the Corpusmla and the Archegonia of the Cryptogamia. See Hofmeister, 

 ^^ Keimung, Mntfalimfig, (he, der holier. Orypfogamen,^^ &e., Leipzig, 1851 j 

 also reported in Henfrey " On the Eeprod. oftJm Oryptoga/mml^ &e. — " Ann, 

 of Nat History;' Set. 2 ix. 1852." 



