n8 



ASCOMYCETES AND RHODOPHYCE^E. 



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, 



FIG. 46. Fusion of sexual nuclei and immediate subsequent development of fecundated 

 egg in Batrachospermum. (After Osterhout.) 



D, sexual nuclei in act effusing ; 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 



