I 124 ) 



TRANSLATIONS. 



On the Impregnation and Germination of Alg^. By M. 

 Pringsheim. (Abridged from the Reports of the Berlin 

 Academy.) 



(Continued from page 72.) 



Having thus fully described the mode of origin of what 

 may be termed the sexual organs in Vaucheria, the author 

 proceeds to describe the process of impregnation as it takes 

 place in the Fucacecc, and which he finds to be of a precisely 

 analogous nature. Adverting to Thuret's observations and 

 experiments, which showed that unless brought into contact 

 with the antheridia of the male ])lant, the spores of these 

 plants invariably perish without germination, he proceeds to 

 relate his own researches on the same subject in Fuciis vesi- 

 culosris. The result was fully to confirm Thuret's statements. 



The density and opacity of the contents of the so termed 

 spores in the FucacecB, render them much less fitted for 

 microscopic examination than are those of Vaucheria, never- 

 theless the author arrived at some important conclusions. 



In Fucus vesiculosus, however, it is not the spore which is 

 impregnated. The so-termed spore of this plant is a large 

 thick-walled cell, densely filled with granular contents, and 

 supported on a unicellular peduncle. When mature the con- 

 tents of this spore divide into eight segments, which the 

 author terms " division-spores" (Theilsporen). When arrived 

 at this stage the contents of the spore are expelled from the 

 transparent thick spore-membrane, and through the opening 

 of the conceptacle (Hiillenfrucht). This usually takes place 

 when the plants have been left dry by the retreat of the tide. 

 Under the same circumstances the antheridial sacs of the 

 male plant are also ejected through the opening of the con- 

 ceptacle. 



When the tide returns and the plants are again covered with 

 water, the antheridia burst exactly as described by Thuret and 

 Decaisne, and allow the mobile spermatozoids to escape, which 

 spread themselves in all directions, and reach the " division- 

 spores" which have collected themselves around the orifice of 

 the conceptacles in the female plant. These sporules, which 

 at the moment of their escape were imbedded in a common 

 gelatinous matrix (fig. 21), have in the mean while become 



