352 CALIFORNIA ACADEMY OF SCIENCES. [Proc. 3D Ser. 



(^) . According to the hypothesis put forward in this 

 paper, attempting to explain the meaning 

 and homologies of the lodiculae in the flower 

 of Avena, they are to be considered as 

 homologous to the stipular lodiculae of the 

 rye. Perianthal lodiculae are not present 

 in the flower of the oat. 

 II. {a). The earlier growth of the stamen is mainly 

 intercalary in the anther; immediately be- 

 fore the pollen is shed the filament elon- 

 gates and causes the anther to protrude 

 from the flower. 

 • {b). The archesporium is composed of a single 

 row of cells originating in the periblem, 



{c) . Each spore mother-cell reaches to the tapetum ; 

 none being bounded only by its fellows. 



{d). In the young anther three concentric rows of 

 cells intervene between the loculus and the 

 epidermis. Of these the tapetum and the 

 middle series are resorbed, and the endo- 

 thecium persists to form with the dermat- 

 ogen the anther wall. 



{e). In the mature pollen-spore the generative 

 nucleus has already divided. 

 III. («). The archesporium of the embryo-sac is of 

 hypodermal origin. 



{b). The sister cells (potential macrospores) are 

 variously formed. The nucleus of the 

 archesporial cell divides to form four sister 

 nuclei. These may be separated as soon as 

 formed by cell-walls, or (2) they may some- 

 what later be separated by the subsequent 

 formation of walls, or (3) they may never 

 become separated, walls never forming. 



{c). The lowest sister cell becomes the macrospore. 



{d). There are no tapetal cells in Avena. 



(e). The antipodals multiply before fertilization 

 of the egg to the number of 36 or more, 

 and disappear as the endosperm develops. 



