118 ON SAPROLEGNLE. 



be regarded as the fecundating corpuscles. After the evacuation 

 of the antheridia, the gonospheres are found to be covered -with 

 cellulose ; they then constitute so many oospores, with solid walls, 

 if I may use an expression specially applied to the alga? by M. 

 Pringsheim. Phenomena which are analogous in several respects 

 and have been studied in the Vaucherice and other conferva?, as also 

 direct observations which are due to M. Pringsheim, do not permit 

 of any doubt but that the cellulosic membrane, which appears on 

 the surface of the gonospheres, is only the consequence of sexual 

 fecundation, and that this ought not to be attributed to the cor- 

 puscles which issue from the antheridea, which would penetrate 

 into the gonospheres, and unite with their substance. 



In Saprolegnia dioica and Achlya dioica, the gonospheres and 

 the oogonia are formed in the manner we have just described ; the 

 membrane of these latter is pierced with openings or pores, and 

 yet no antheridia-bearing filament is seen to be applied to it. It 

 must be elsewhere that M. Pringsheim has seen organs which 

 everything authorizes us to qualify as antheridia. Thick tubes, 

 similar to those which engender the zoospores, spring from the 

 mycelium at a given moment, and are divided by septa into a series 

 of cylindrical cells, each of which is an antheridium. In Sapro- 

 legnia dioica, the plastic contents of the antheridia are transformed 

 into an infinitude of very small vacillary corpuscles which escape 

 with much agility by the orifice of a prolongation of the anther- 

 idium, made in the manner of a neck and very short. The 

 antheridium of Achlya dioica is cylindrical, the plasma which it 

 encloses is divided into particles which have nearly the volume of 

 the zoospores of the plant. These particles become globose cells, 

 grouped in the centre of the antheridium. Posteriorly the con- 

 tents of these latter cells are divided into numerous bacillary 

 spermatozoids, which first break the wall of their mother-cell, and 

 then issue from the antheridium in the same manner as the sper- 

 matozoids of Saprolegnia dioica. These corpuscles, in the two 

 plants of which we are speaking, resemble the spermatozoids of 

 the Vaucherice ; they are bacillar, and their agility is assisted by a 

 long ciliuni. It is presumable that here, as in the alga?, concern- 

 ing which we have positive demonstration, the spermatozoids intro- 

 duce themselves into the cavity of the oogonium, and unite with 

 the gonospheres. On this point, however, observations are wanting, 

 and therefore we cannot consider ourselves perfectly sure in our 

 appreciation of the organs of which we have just treated. 



We may also class amongst bodies of a doubtful nature, but 

 which are certainly worthy of further observation, the organs first 

 seen by M. Nageli, then by M. Alex. Braun, and M. Cienkowski, 

 and, lastly, by M. Pringsheim, who has carefully described them, 

 and who considers them to be the probable antheridia of some 

 species of Achlya or Saprolegnia. These bodies, according to the 

 learned Professor of Jena, have their origin in thick filaments or 



