118 ASCOMYCETES AND RHODOPHYCEA. 
basal part of the carpogonium now becomes narrower and is finally 
closed by the swelling or growth of the cell-wall, so that the entrance 
of other male nuclei is impossible (Fig. 46, D). In case other male 
nuclei enter the trichogyne from other adhering spermatia, as frequently 
happens, these fragment and disappear, and the same fate befalls those 
nuclei that remain in other adhering spermatia. Soon after the male 
nucleus enters the trichophore it fuses completely with the egg-nucleus 
(Fig. 46, D, E). This fact, so unmistakably observed by Osterhout, 
Fic. 46.—Fusion of sexual nuclei and immediate subsequent development of fecundated 
egg in Batrachospermum.—(After Osterhout.) 
D, sexual nuclei in act of fusing; an empty spermatium adheres to tip of trichogyne. 
E, later stage; the trichophore has increased in size and sent out a protuberance; the 
empty spermatium which has copulated with the trichogyne has furnished the male 
nucleus; below it is a spermatium with a nucleus, and above to the left is one in 
which the nucleus has undergone fragmentation, 
leaves no room for doubting the existence of a true fecundation in 
Batrachospermum. 
Schmidle did not observe the actual fusion of the sexual nuclei, but 
he concludes that the same takes place. He asserts that, together with 
the two nuclei which he finds in the spermatium, a portion of the cyto- 
plasm also enters the trichogyne, while the plasma membrane remains 
behind, save in exceptional cases in which the spermatia were quite 
empty. Davis (’96) having failed to observe the entrance of the male 
nucleus into the egg-cell, inclined to the view that only cytoplasmic 
contact was necessary in Batrachospermum to insure the further 
