ELEMENTARY BIOLOGY. [CHAP. 



/2. The root-hairs : each composed of a single 

 cell which contains no chlorophyll. 



c. The antheridia and archegonia : the former can 

 just be seen with an inch objective as minute 

 eminences on the under surface of the older 

 parts of the prothallus especially among the 

 root-hairs; the latter are partly imbedded in 

 the cushion. 



b. The reproductive organs. 



These are to be found by examining the under surface of 

 the prothallus with obj. 



1. The antheridia. Most numerous near and among the 

 root-hairs. 



a. Their form : small hemispherical eminences. 



b. Their structure: made up of an outer layer 

 of cells containing a few chlorophyll-granules, 

 through which can be seen, according to the 

 stage of development, either a single central cell, 

 or a number of smaller cells (mother-cells of 

 spermatozoids} resulting from its division : in the 

 latter cells, in ripe antheridia, spirally coiled 

 bodies (spermatozoids) can be indistinctly seen. 



2. The spermatozoids. 



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 spermatozoid is often attached 

 a rounded mass containing colourless granules. 



