DR. M. J. SCHLEIDEN ON PHYTOGENESIS. 289 



sorbed cotemporaneously with it. Yet I have also observed 

 that the latter in the middle period of its existence lost much of 

 its distinctness and sharpness of outline, which however reap- 

 peared when the reabsorption had commenced ; for instance, in 

 the nucleus of the ovules of Abies excelsa, Tulipa sylvestris, and 

 Daphne alpina. It is inconceivable how some physiologists 

 have been able to deny reabsorption in plants, since even very 

 considerable portions of cellular tissue, for instance of the nu- 

 cleus of the ovule, become wholly fluid again, and are received 

 into the common mass of sap. This indeed only takes place so 

 long as the cell still consists of the simple original membrane, 

 and whilst it is not so far advanced in its individual development 

 that its wall is thickened by secondary deposits. 



3. In some rare cases the cytoblasts also remain persistent in 

 the pollen granules ; this is the case in some, perhaps all the 

 AbietifKB. The lenticular cytoblast has already been obser\^ed 

 by Fritzsche in Larix europcea, but its nature not understood. 



4. Many hairs, especially the articulated and such as exhibit 

 circulation of the sap in their cells, retain the cytoblasts {c,f. fig. 

 25.). It is remarkable, and moreover a proof of the close relation 

 in which the cytoblast stands to the whole vital activity of the 

 cell, that the small currents frequently covering the entire wall 

 reticularly, always proceed from it and return to it, and that in 

 statu integro, it is never situated without the current (fig. 25.). 



The above described development of the cells I have observed 

 in their whole course in the albumen of Chamcedorea Schiedeana, 

 Phormium tenax, Fritillaria pyrenaica, Tulipa sylvestris, Elymus 

 arenarius, Secale cereale, Leucoji spec, Abies excelsa, Larix eu- 

 ropcea. Euphorbia pallida, Ricinus leucocarpa, Momordica elate- 

 rium, and in the embryonal end of the pollen cell of Linumpal- 

 lescens, (Enothera crassipes, and a number of other plants. It 

 was only in the summer of 1837, after this memoir had been 

 written, that I took up the examination of the LeguminoscB, and 

 found to my surprise that in these plants, so frequently examined 

 and everywhere employed as examples in the history of vege- 

 table development, this process, overlooked by all observers, 

 might most beautifully and easily be studied. But, indeed, 

 the saccharine fluid contained in the embryonal sac had not 

 been considered worth examining. 



Without exactly following up the whole course of the forma- 

 tion of the cells, I found the cellular nuclei previous to the oc- 



