THE DIFFERENTIATION OF FLOWER-BUDS 39 



distinctly four-lobed, each lobe representing a distinct 

 microsporangiuni. The microsporangia pass the winter in 

 the mother cell stage. Only slight changes take place during 

 the early part of the winter up to the middle of Februaiy or 

 the middle of March, when more active growth again takes 

 place. 



''The stamens in the outer cycle are borne in pairs side 

 by side at an acute angle to the sepals, while the two inner 

 cycles are bonie at nearly right angles to the calyx lobes. 

 Furthermore, of each pair of stamens in the outermost cycle 

 one stands at either side the middle line of each calyx lobe, 

 each stamen in the next cycle of five stands opposite each 

 petal, while each stamen in the innermost cycle of five stands 

 opposite the middle axis of each sepal, thus alternating with 

 the middle cj^cle of stamens by which they are partially 

 overlapped in the bud. The outermost series stands more or 

 less erect and after the expansion of the petals are the first to 

 dehisce, the two inner cycles remaining incurved and bent 

 down for a varying length of time, depending on environ- 

 mental conditions. They soon l^ecome erect, however, and 

 shortly thereafter dehiscence of the anthers and discharge 

 of pollen occurs." 



40. Carpels. — "The five primordia for the carpels are 

 the last to appear, doing so inunediately after the primordia 

 of the proximal cycle of stamens have been laid down. They 

 are bome immediately within the innermost cycle of stamens 

 and some distance from the center of the torus, which is now 

 apparently lower than the outer edges which have been under- 

 going elevation continuously; the torus, accordingly, has 

 become distinctly cup shaped at this time. 



"The primordia of the carpels like all other structures 

 previously mentioned, appear first as short blunt protuber- 

 ances arising from th(^ torus. Directly after this very early 

 beginning, growth does not proceed equally in all directions 



