4 , ') '^ PHA NER OGA MS . 



lunnel of the endosperm. The tube entirely fills up the funnel and applies itself to 

 the necks of the whole group of archegonia ; short narrow protuberances from the 

 wide pollen-tube now grow into the separate necks of the archegonia, forcing the 

 stigmatic cells from one another and destroying them, and at length reaching the 

 central cell. The same process takes place in the Abietineae and Taxinese ; the 

 pollen-tube, after widening again, becoming narrower and entering the neck of 

 only one archegonium, whence it penetrates finally as far as the central cell. A 

 thin spot may be observed at the extremity of this protuberance of the thick- 

 walled pollen-tube, which obviously facilitates the escape of the fertilising substance 

 by diffusion ; and this is probably assisted by the pressure exerted by the tissue 

 which lies above on the part of the pollen-tube outside the archegonium. Hof- 

 meister states that a few free primordial cells (Fig. 325, /) are sometimes formed 

 in the end of the pollen-tube, which he was inclined to consider as rudimentary 

 indications of mother-cells of antherozoids (corresponding somewhat to those in 

 Salvinia) ; but Strasburger denies the existence of bodies of this kind, and admits 

 only the presence of a number of grains of starch in the protoplasm at the end 

 of the pollen-tube. In reference also to the processes in the central cell of the 

 archegonium, the statements of these two observers differ. According to Hof- 

 meister a number of primordial cells arise in the protoplasm of the central cell, all 

 of which he considers to be embryonic vesicles (oospheres) ; one of- these, however, 

 is distinguished from the rest even before fertilisation by its size and contents; it 

 lies in the upper or middle part of the central cell, but after fertilisation sinks to 

 its base and adheres closely to it, filling up the lower part of the central cell as 

 the rudiment of the embryo, while the remaining embryonic vesicles perish. Stras- 

 burger, on the contrary, considers the whole protoplasmic contents of the central 

 cell as the ' oosphere,' and regards Hofmeister's numerous embryonic vesicles only 

 as vacuoli (vesicles of protoplasm). The effect of fertilisation is manifested first 

 of all in the central cell by the turbidity of the protoplasm and by the formation 

 of granular bodies in it ; these collect in the lowTr part of the central cell, which 

 then becomes separated by a septum from the larger remaining part, and forms the 

 rudiment of the pro-embryo. Our figures, which are borrowed from Hofmeister 

 (Fig. 324,^, X, and 325, /, ei, the rudiment of the pro-embryo mentioned above), may 

 point to both explanations ; that of Strasburger, however, is most in accordance with 

 the processes that take place in the archegonium of the highest Cryptogams, as 

 well as with those in the embryo-sac of Angiosperms, and connects the two. My 

 own observations, however, are not sufficient to decide definitely in favour of one or 

 the other view. 



The further development of the rudiment of the pro-embryo (Fig. ^24, A, x, 

 and Fig. 325, /, ei), is brought about by longitudinal divisions at right angles to 

 each other, which are soon followed by transverse divisions ; a mass composed 

 usually of three layers of cells is thus formed at the base of the central cell ; the 

 bottom of the cell is broken through by a considerable extension of the uppermost 

 (in Taxus and Juniperus) or middle cells (Abietineae) of the pro-ernbryo (Fig. 324, 

 B, v) ; these cells elongate, continue to grow, and transverse divisions are formed 

 in them (Fig. 325, IV, v), and penetrate into the softened part of the endosperm, 

 bending in different directions. In Taxus the elongated cells of the pro-embryo 



