BOTANICAL SUBJECTS. 



227 



In anthers of Magnolia and Liriodendron, and of* the Pines, 

 give us, perhaps, some of the best examples of what I have been 

 trymg to impress the reader ^vith, viz., the apparently strong 

 homology between the anther sacs or locelli and the sori of ferns, 

 and more especially so with those of Pteris aquilina. 



Histology appears to tell us little about the homology of 

 the anther. It tells us that out of a mass of parenchyma or 

 common cells, certain cells become differentiated, that is, they 

 grow differently, and take on different characters. These then 

 give rise to mother cells, which change into tetrads. Then the 

 protoplasm in the cells of a tetrad becomes covered with a new 

 cell-wall, which is the cell-wall of the pollen grains.* The 

 transformation of the mother cells into tetrads is shown in Fig. 79. 



Fig. 79. Section of young anther of Melon, with two cells filled with 

 mothei cells (Le Maout and Decaisne, Fig.. 702) : (a) mother cell of the 

 same, originally hexagonal, containing four pollen grains (tetrads). 



Histology has no doubt shown us that these tetrads, under various 

 names, are to be found wherever reproductive cells are to be found, 

 from the frond of Porphyra, as Thuret has shown, to the anthers 

 of melons, &c. 



We have, therefore, to compare other organs of other plants, 

 after freeing our minds from the bias of words and books. The 

 study of the emergence of the sori of ferns affords, perhaps, a 

 good schooling for the study of the morphology of the anther. 

 We must imagine the fern leaf as divested of mesophvl, which is 

 only a sort of glue with a special function, which fasciates the 



* Goodale, "Phisiol. Bot.," p. 171. 



P '1 



