2-28 THE PHKNOMENON OF 



pollen-cells in their special mother- cells.* The whole 

 conception of the formation of new cells (daughter-cells) 

 in old ones (mother-cells), as it has grown up since first 

 brought forward by Schleiden,t now requires a further 

 elucidation, since it has been extended from the so-called 

 free cell-formation, to which alone it is perfectly applicable, 

 to the far more common cell-formation by division, whence 

 has arisen a nomenclature, to the equivocal character of 

 which I must here direct attention. It is a mistake to apply 

 the word cell sometimes to the cell with a viemhrane, some- 

 times to the cell without a membrane, and sometimes to 

 the membrane without the cell. Since the contents of 

 the cell constitute the essential part of it (see p. 155), 

 since it forms, before the secretion of the (cellulose-) 

 membrane (pp. 156 — 167), a separate entity, possessing 

 its own, essentially proper, membranous boundary (the 

 primordial utricle, pp. 169 — 173), we must call this 

 internal body the cell proper, unless we restrict the term 

 cell to the enclosing wall or chamber, and give the 

 internal body another name. If the name is restricted 

 to the internal body, we cannot, in the great majority of 

 cases, say that new cells are formed in the old, but 

 merely that they are formed out of the old, for even the 

 primordial utricle shares in the division, in the propa- 

 gation of cells by division. Therefore when daughter- 

 cells are said to be formed in the mother-cells, or to slip 

 out from the mother-cells, or mother-cells are said to be 

 dissolved and absorbed, these phrases must be admitted 

 only as conveniently abbreviated expressions, "mother- 

 cell" being here used instead of maternal cell-membrane. 

 Finally, there are cases in which the expression, that 

 daughter-cells are formed in mother-cells, cannot be ap- 

 plied, even in this abusive sense ; these are the cases 

 above mentioned (p. 159) of division of cells which pos- 



* According to Hofmeister (' Ueber die Entwieklung des Pollens,' Bot. 

 Zeit., 1848, p. 431), the nucleus even survives this transition. 



f " The process of propagation of cells by the production of new cells in 

 their interior, is the general law in the vegetable kingdom." (Sohleiden, 

 ' Grmidz.,' 2 Aufl. i, p. 305, ' Principles,' p. 103.) 



