BOTANY. 



some of them finally reach the oosphere (through a rupture 

 in its wall), and unite with its protoplasm (E, F). The re- 

 sult is at once seen in its greater sharpness of outline, and 

 in the development of a cell-wall, whereby the oosphere is 

 transformed into an oospore. 



60. Essentially the same kind of union takes place in the 

 nearly related parasitic group, the Peronosporece. The only 

 difference is that here the antheridium (Fig. 39, n) comes in 

 direct contact with the oosphere (o) by means of a project- 

 ing tube, and through this tube the protoplasm masses of 



the two cells unite. 

 The absence of mo- 

 tile spermatozoids 

 in this case is prob- 

 ably connected with 

 the fact that these 

 plants live in the 

 tissues of land 

 plants, instead of 

 being immersed in 

 water. 

 61. The first cell 



t] Si> of the embryo in 



mosses is the result 



Pig. 37. Filamentsof Spirogyra longata; in A, at a n e lir ,i nri n f ppllc 



the protoplasm is passing from the lower cell to the up- L 



per ; at b the union of the two protoplasmic masses is differing great! V in 

 completed ; in B the protoplasmic masses have ge- o fe J ' 



creted thick walls, thus completing the formation of size. The larger 

 the new cells. X 550. After Sachs. ,. 



cell lies at the bot- 

 tom of a flask-shaped organ, the archegonium (Fig. 40, B, 

 b) ; the smaller, the spermatozoids, are developed by the in- 

 ternal cell-division of another organ, the antheridium (Fig. 

 41, A). The spermatozoids, as in Vaucheria, are naked 

 masses of protoplasm, provided with cilia, by means of 

 which they swim freely through the water (Fig. 41, B}. 

 Upon coming in contact Avith the large cell in the archego- 

 nium they fuse with it, and thus make a new cell. 



62. In Phanerogams the first cell of the embryo is the re- 

 sult of the union of the protoplasm contained in the pollen- 

 cell with that in the embryo sac. Here again the two 



