VAUCHERIA. 77 



most part colourless : when mature the contained proto- 

 plasm forms a large number of small antherozoids, 

 which escape through an opening which appears at, 

 the apex. 



By a comparison of a number of specimens various stages of 

 development of the antheridium may be observed : e.g. (1) its origin 

 as a rounded papilla from the main filament ; (2) the appearance 

 of the septum ; (3) the opening of the pore at the apex, and escape 

 of the antherozoids; (4) the empty wall of the antheridium with 

 the pore at the apex through which the antherozoids have escaped ; 

 (5) the form of the antherozoids and their cilia are to be observed 

 in specimens stained with iodine solution. 



Next examine a mature oogonium in detail : note 

 its sessile position, and the septum which separates it 

 from the main filament : its oblique form and green- 

 coloured, granular contents : when actually mature an 

 obliquely lateral beak is formed, the apex of which 

 becomes gelatinous, so that the motile antherozoids can 

 gain access to the protoplasm. 



By comparing specimens of different ages the following points 

 may be observed : (1) the origin of the oogonium as a rounded 

 outgrowth from the main filament ; (2) the appearance of the 

 septum ; (3) the opening of the apex of the beak, and extrusion of 

 a portion of the protoplasmic body, leaving exposed the colourless 

 receptive spot ; (4) attempts should be made to observe the actual 

 entry of the antherozoids. 



It is stated that the development of the sexual organs takes 

 place at night, and the process of fertilisation during the day, the 

 whole being completed within the twenty-four hours. 



IV. Observe the changes which succeed fertilisation, 

 resulting in the formation of the ripe oospore : the 

 chief are 



1. Formation of a firm wall completely surrounding 



