xx STRUCTURE OF SPERMARY 213 



on the inner surface only, the spermary appears to have a 

 colourless transparent outer layer like an orange inclosed 

 in a close-fitting glass case. 



Attached to the middle of the inner surface of each shield 

 is a cylindrical cell, the handle (/in), which extends towards 

 the centre of the spermary, and, like the shield itself, con- 

 tains orange chromatophores. Each of the eight handles 

 bears a colourless head-cell (hd), to which six secondary head 

 cells (hd') are attached, and each of these latter bears four 

 delicate coiled filaments (sp.f.) divided by septa into small 

 cells arranged end to end, and thus not unlike the hyphse of 

 a fungus. There are therefore nearly two hundred of these 

 spermatic filaments in each spermary, coiled up in its interior 

 like a tangled mass of white cotton. 



The cells of which the filaments are composed have at 

 first the ordinary character, but as the spermary arrives at 

 maturity there is produced in each a single sperm (c), having 

 the form of a spirally-coiled thread, thicker at one end than 

 the other, and bearing at its thin end two long flagella. In 

 all probability the sperm proper, i.e., the spirally coiled body, 

 is formed from the nucleus of the cell, the flagella from its 

 protoplasm. As each of the 200 spermatic filaments con- 

 sists of from 100 to 200 cells, a single spermary gives rise 

 to between 20,000 and 40,000 sperms. 



When the sperms are formed the shields separate 

 from one another and the spermatic filaments protrude 

 between them like cotton from a pod : the sperms then 

 escape from the containing cells and swim freely in the 

 water. 



The ovary (Fig. 44, G, ovy, and Fig. 47 A) is ovoidal in 

 form, attached to the leaf by a short stalk (stk\ and ter- 

 minated distally by a little chimney-like elevation or crown 

 (cr). It is marked externally by spiral grooves which can be 



