226 



ELEMENTS OP BOTANY. 



tained in the expanded portions, /. In these expansions 

 there are produced somewhat spherical bodies, A, Pig. 197, 

 which may be called egg-cells {pospheres), and ciliated fertil- 

 izing cells, or antherozoids, G. After the bursting of thei 

 thin membrane, shown at A, by which the egg-spheres are 

 confined, they become covered with multitudes of the fertiliz- 

 ing cells, as seen at F and H, and are often whirled about 

 by the motion of the cilia of these cells. At length, the sub- 



FiG. 197. — Production of Spores of Eookweed. (Much magnified.) > 

 A, a bundle of egg-spheres, or oospheres (from interior of/, Fig. 196); O, ciliated 

 fertilizing cells, or antherozoids (from interior of /, Fig. 196) ; F, H, egg-spheres 

 changing to spores by union of fertilizing cells with their contents. (G is magni- 

 fied more than twice as much as the other parts of the figure.) 



stance of one of the ciliated cells becomes mingled with that 

 of the naked protoplasmic egg-sphere, and the latter soon 

 proceeds to develop a cell wall and begins at once to grow 

 into a new plant of rockweed. 



THE STUDY OF YEAST. 



276. Growth of Yeast in Dilute Syrup. — Mix about an eighth of a 

 cake of compressed yeast with about a teaspoonf ul of water and stir until 

 a smooth thin mixture is formed. Add this to about half a pint of water 

 in which a tablespoonful of molasses has been dissolved. Place this mix- 



1 A and -F of this figure represent the spore-producing apparatus from Fucus 

 platycarpus. Fig. 196 is FiKUs vesiculosus. The principle of spore-formation is very 

 similar in the two species. 



