432 Dr. W. Hofmeister on the Fecundation of the Coniferse. 



originally contains only one very large central vacuole ; the pro- 

 toplasm of the contents of the corpusculum forms a layer over 

 the wall, on which the primary nucleus of the cell is imbedded*. 

 This condition is at an end early in the Abietinese, in Pinus 

 sylvestris at the beginning of June. The watery fluid which filled 

 the vacuoles becomes distributed into the continually multiplying 

 smaller globular cavities of the protoplasm, the dimensions of 

 which become progressively smaller in proportion to the total 

 internal cavity of the still constantly enlarging corpusculum. The 

 free globular cells now make their appearance outside these 

 vacuoles, which from this time disappear one after another. This 

 condition is particularly evident in Pinus canadensis, where one 

 or two of these vacuoles still exist shortly before the impregna- 

 tion, among the collection of floating cells which fill up the whole 

 corpusculum. That the said structures are cells is proved, not 

 only by their aspect and the presence of a nucleus, but more 

 particularly by their often-observed multiplication t- 



In the Cupressinese the one central vacuole, and also the pri- 

 mary nucleus of each corpusculum^ are retained until a short time 

 before the impregnation. A few days only (the space of time 

 cannot be stated accurately on account of the seeds of the 

 Cupressinese not being developed simultaneously ; I have every 

 reason to believe it is at most forty-eight hours) before the 

 pollen-tubes reach the upper ends of the corpuscula^ by push- 

 ing aside the rosettes of cells covering them, the single vacuole 

 becomes broken up into several, between and especially above 

 which the formation of free spherical cells takes place. Mean- 

 while the primary nucleus of the corpusculum slowly disappears ; 

 its nucleoli remain visible longer than its membrane. 



In general, among the numerous daughter- cells of the corpus- 

 cula, those situated in the upper end, next the micropyle, are 

 farther developed than the rest. While the latter appear desti- 

 tute of a membrane, as 'primordial cells ^ (naked primordial 

 utricles), the former are usually enclosed in a demonstrable cel- 

 lulose coat ; in the Firs {Pinus sylvestris, austriaca, maritima) often 

 appressed against the wall of the corpusculum or impressed into its 

 upper convexity, like the germinal vesicles of the Monocotyledons 

 and Dicotyledons ; in the Pines [Pinus Picea, L., and canadensis) 

 mostly swimming free, not globular however here, but ovate. 

 In Taxus, where the number of comparatively large cells appear- 

 ing free in the corpusculum is but small, a single one ordinarily 

 swims free in the centre of the corpusculum, while the remainder 

 adhere to various points on the wall. Here, there is not the 



* Ihid. t. 28. figs. 4, 5. 



t Vide Pineau, Ann. des Sc. Nat. 3 ser. xi. pi. 6 ; and my Vergleich. 

 Untersuch. pi. 2.9. figs. 1, 3-5. 



