31^(5 M. E. Claparede on the Theory of the 



which the canal with which this organ is furnished leads ; tfefp 

 are also the homologiies of the embryonal sac of the Phanero-^ 

 gamia. It appears that the central cell of the archegonium 

 contains no trace of the embryonal cell before fecundation 

 (Pringsheim), and that the latter is only formed subsequently, 

 after the entrance of the sperraatozoids, surrounding a portion 

 of the contents of the central cell, and enclosing the sperma- 

 tozoids. 



Pringsheim puts the question, whether something of the 

 same kind does not take place amongst the Phanerogamia, and 

 whether the extremity of the pollen-tube, which penetrates into 

 the embryonal sac, does not contain spermatozoids, which, in 

 common with the contents of the sac, would surround them- 

 selves after this fecundation with a fine membrane, and thus 

 give rise to the first cell of the embryo. Such an hypothesis* 

 has no want of probability for those who admit Schleiden's 

 theory, which, it must be confessed, has made some progress 

 during the last few years. For my part, Henri Schacht has 

 shown me some very delicate preparations which appeared to 

 speak strongly in its favour, and which would have completely 

 convinced any person who did not bear in mind the difficulty 

 there is in such remarkably fine preparations in distinguishing 

 what is interior from what is above or below. I have also exa- 

 mined Deecke^s famous preparation (a longitudinal section of the 

 ovule of Pedicularis sylvatica, with a pollen-tube which has 

 penetrated into the embryonal sacf), which appears to me to be 

 strongly in favour of Schleiden, notwithstanding all the objec- 

 tions which MohlJ has brought against it. In any case, the 

 analogy with what takes place in the Cryptogamia and in animals 

 comes in as evidence in favour of the defenders of Schleiden^s 

 theory ; and although there is no doubt that in the inductive 

 sciences we must be as careful as possible about reasoning from 



* It is, moreover, perfectly possible that the presence of spermatozoids 

 may not be absolutely necessary throughout; and it is not improbable 

 that a liquid may play their part. 



t See an article by H. Schacht, Flora, 1855, Nos. 10 and 11. 



X Der vorgebliche entscheidende Sieg der Schleidenschen Befruchtungs- 

 theorie. Bot. Zeit. 11th June, 1855. These objections, however, are not 

 of much value veith respect to our present subject. Thus, Mohl first objects 

 that the so-called pollen-tube might very probably be the suspensor of the 

 embryo issuing through a rent in the sac, although it appeared to Mohl 

 himself to be a pollen-tube. Tlie argument is not one of the strongest. 

 Mohl then passes to the second point ; that is to say, he denies that the 

 extremity of the pollen-tube forms the embryo, without however pretending 

 to dispute that this pollen-tube may penetrate into the embryonal sac. But 

 we ask nothing more to furnish the analogy with the Cryptogamia and 

 animals, for in the hatter also it is not proved that the embryo is directly 

 produced from the spermatozoid or spermatozoids. 



