C6 ELEMENTARY BIOLOGY. [VII. 



dral chlorophyll-containing cells, but at parts 

 it is more than one cell thick. 

 /3. The rootlets: composed of a series of cells 



which contain no chlorophyll. 



c. The antheridia and archegonia: these can just be 

 seen with an inch objective as minute eminences 

 on the under surface of those parts of the 

 prothallus which consist of several layers of 

 cells. 



b. The reproductive organs. 



These are to be found by examining the under surface of 

 the prothallus with J obj. 



1. The antheridia. Most numerous near and among the 

 rootlets. 



a. Their form: small hemispherical eminences. 



b. Their structure: made up of an outer layer 

 of cells containing a few chlorophyll-granules 

 and through which can be seen a number of 

 smaller cells which occupy the centre of the organ : 

 in the latter cells, in ripe antheridia, spirally 

 coiled bodies (antherozooids) can be indistinctly 

 seen. 



2. The antherozooids. 



Some of these are sure to be found swimming about in 

 the water if a number of ripe prothalli are examined. 



a. Small bodies, coiled like a corkscrew, thick at 

 ... ^ one end, and tapering towards the other, which 



has a number of cilia attached to it. To the 

 thicker end of the antherozooid is often attached 

 a rounded mass containing colourless granules. 



b. Treat with iodine ; this stains them and stops 



