1885.] NEW-YORK MICROSCOPICAL SOCIETY. 13 



sperm from South Africa) the corpuscula develop into long 

 tubes within the nucellus, meeting the pollen-tubes. 



The editor of the "Journal of the Royal Microscopical Society" 

 thus sums up the results of Detmer's observations : "The growing 

 pollen-tubes receive their formative materials from the mucilag- 

 inous and amyloid substances secreted by secreting organs on 

 the stigma, and in the stylar canal and interior of the ovary. 

 These secreting organs are more or less papillose. * * * * 

 Besides providing nutrition for the pollen-tubes, these papillose 

 structures furnish also a conducting tissue to guide the pollen- 

 tube * * * * to the micropyles of the ovules. * * 

 * * Seeing that this tissue reaches up to the very micro- 

 pyle itself, and that it only can supply the pollen-tube with the 

 nutriment it requires, it follows that the entrance of the pollen- 

 tube into the ovule is purely a mechanical phenomenon and does 

 not depend on any mysterious relationships between the pollen- 

 tube and the embryo-sac." 



The most elaborate investigations on the whole subject of 

 vegetable impregnation are those of E. Strasburger. Indeed, 

 they are given in such minuteness of detail that I cannot hope 

 in an article of this kind to present even an abstract of them ; 

 and I will merely name, in a foot-note, some of the publications 

 in which they are to be found. ^^ An examination of the results 

 reached by this distinguished physiologist cannot fail to con- 

 vince the reader of the truth of the statement that pollen-tubes 

 enter the ovules and deposit part of their contents. 



Hofmeister also has contributed largely to the literature of 

 these phenomena. 



Bessey thus describes the impregnation of the ovule in Gym- 

 nospermse,^^ and he illustrates it with diagrams of the fertilized 

 ovule in Pinus Larico after Strasburger, and of Juniperus com- 

 munis after Hofmeister : — 



" Fertilization is effected by means of the pollen, which comes 

 in contact with the apex of the ovule. * * * * When the 

 ovule has reached the proper stage the micropyle is filled with a 

 fluid, which, drying, carries the adherent pollen grains into con- 

 tact with the apex of the ovule body, where they germinate and 

 form pollen-tubes : the latter penetrate the soft tissue of the 



"^''tTeberZellbildungundZelltheilung," Jena, 1875; "Die Befruchtung bei den 

 Coniferen," Jena, 18?'2 ; " Ueber Befruchtung und Zelltheilung," Jena, 1877. 

 22" Botany for High Schools and Colleges," 1880, p. 403. 



