PIIYT0GENES1S. ,!i 



margin of the cytoblast, and quickly becomes so large thai the 

 latter at last merely appears as a small body enclosed in one 

 of the side walls. At the same time the young cell frequently 



exhibits highly irregular protrusions (fig, 1, c), a proof that 

 the expansion by no means proceeds uniformly from one point. 

 During the progressive growth of the cell, and evidently arisi] 

 from the pressure of the neighbouring objects, the form be- 

 comes more regular, and then also frequently passes into that 

 of the rhomboidal dodecahedron, so beautifully defined a priori 

 by Kieser. (Compare fig. 1, from b to e, with fig. S.) The 

 cytoblast is still always found enclosed in the cell-wall, in 

 which situation it passes through the entire vital process of the 

 cell which it has formed, if it be not, as is the case in cells 

 which are destined to higher development, absorbed either in 

 its original place, or after having been cast off as a usel< 

 member, and dissolved in the cavity of the cell. So far as I 

 could observe, it is only after its absorption that the formation 

 of secondary deposits commences upon the inner surface of 

 the cell-wall (fig. 9). 



As a general rule, it is rarely that the cytoblast accom- 

 panies the cell which it formed through its entire vital proce 

 nevertheless, it is, 



1. Characteristic of the families of the Orchidete and CacU 

 that in them a portion of their cellular tissue remains in a 

 lower stage of development during the entire period of life. 



2. In various plants it occurs that cellular tissue, which fa 

 merely a transitory signification, is not perfectly developed. 

 but retains the cytoblast, and is absorbed together with it at a 

 subsequent period. Yet I have also remarked that the latter 

 in the middle period of its existence lost much of its distinct- 

 ness and sharpness of outline, which, however, reappeared when 

 absorption commenced; for example, in the nucleus of tin 

 ovule of Abies excelsa, Tulipa sylvestris, and Daphne alpina. It 

 is most extraordinary that some physiologists should haw frit 

 prepared to deny the fact, that absorption takes place in plant 

 since even very considerable portions of cellular tissue of the 

 nucleus of the ovule, for instance, become completely fluid 

 again, and are received into the common mass of the sap. It 

 is true this only takes place so long as the cell still consist 

 of the simple original membrane, ami i^ not so far advanced 



