202 Dr. H. Karsten on the Sexual Life of 



In the embryo-sac the observer has all the different stages of 

 cell-development before his eyes at the same time, and yet he is 

 without a clue to the order of their origin ; consequently his 

 judgment may be at fault whether to admit that the outer cell 

 is gradually deposited, in a laminated fashion, upon the inmost 

 cell or nuclear corpuscle, or that the inner cells originate in the 

 fluid contents of the external cells, which in the mean time 

 expand. 



In my Dissertation published in 1843, I remarked on the 

 existence of the " daughter-cell," subsequently termed by Mohl 

 the primordial utricle, and have very many times since recurred 

 to this subject, and I still deem it incumbent on me again to 

 make the assertion that the formation of a cell-membrane as a 

 deposit on a mucoid, cellular, &c., nucleus, has, according to my 

 repeated and careful investigations of the subject, no existence 

 in nature. Statements of the sort have arisen wholly from in- 

 correct views of what has been observed, because the phenomena 

 of growth of the membrane and of the chemical changes of the 

 cell-matter wei*e not understood ; and I may be allowed to com- 

 mend to the consideration of physiologists my paper in Poggen- 

 dorff's Annalen as peculiarly pertinent to the matter in discus- 

 sion respecting the transformations of cellulose in the progress 

 of growth. 



The physico-chemical processes in which the phenomena of 

 cell-growth consist must of necessity be rightly apprehended 

 before we can hope to understand the complicated physiological 

 phenomena of the organism. 



In the case of Ccelebogyne, I am unable, from the want of 

 material, as before said, to assert positively whether the cellular 

 contents had been given birth to before the arrival of the pollen- 

 tube in the embryo-sac — as is probable, because we are acquainted 

 with cases where albuminous tissue is commenced about barren 

 (non-germinating) seeds — or whether the cell-contents first arise 

 as a consequence of the action of the pollen-tube ; and further, 

 whether the commencement of germ-growth in some of these 

 cells is induced by the contiguity of the pollen-tube, or if an 

 actual contact of the two is needed. This relation is of mo- 

 ment in making the comparison between the commonly occur- 

 ring single germ of the Phanerogamia and vascular Cryptogamia 

 and the usually numerous germs of the cellular Cryptogamia, 

 especially of the Mosses and Liverworts. 



In my ' Flora Columbia?' (p. 41) I assimilate the spores of the 

 Mosses with the polycotyledonous embryos of the Coniferre, be- 

 cause the spores contained in the sporangia of Mosses, like the 

 divided embryos of the Conifera?, originate from the multiplica- 



