246 Practical Plant Biology. 



an outer whorl which is not distinguishable into calyx and corolla 

 is called a perianth. Sometimes the segments of the perianth of 

 the Hyacinth are slightly coherent together by their bases. Im- 

 mediately above the perianth are six stamens. They are attached 

 to the axis, but sometimes adhere to the base of the segments of 

 the perianth. Their filaments are white and tapering while their 

 anthers are blue. The tapering end of the filament is joined to 

 the middle of the connective so that the anther seems to pivot at 

 its middle on the top of the filament. The anthers dehisce 

 longitudinally and shed the pollen. 



The segments of the perianth and the stamens have a similar 

 origin to the sepals, petals and stamens of the Buttercup, i.e. their 

 early stages resemble the early stages of foliage-leaves. Differentia- 

 tion as perianth segments and stamens occurs later. After the 

 anthers and filaments of the stamens have been outlined the four 

 columns of sporogenous cells develop in the anthers, the pollen- 

 sacs, each containing one column, are formed and the con- 

 nective is differentiated. The wall of the pollen-sac, as in the 

 Buttercup, is divisible into two layers, the epidermis and fibrous 

 layer. The latter secures the dehiscence of the pollen-sac by a 

 mechanism similar to that which has been described in the pollen- 

 sac of the Buttercup. The pollen-grains also arise in the mother- 

 cells or sporogenous cells in tetrads just like those of the Buttercup. 



Above the stamens and on top of the axis is a globular capsule 

 tapering upwards into a delicate column ending bluntly in a rough 

 and sticky surface. The capsule is the ovary : the column, the 

 style : and the rough and sticky ending, the stigma. When the 

 ovary is cut across it is seen to be divided into three compartments 

 (loculi) by vertical partitions. There is a groove on the outside of 

 the ovary corresponding to the position of each partition. In each 

 angle formed by the converging partitions there are two rows of 

 minute white bodies which are the ovules. This whole structure 

 above the stamens corresponds to three fused carpels united along 

 their adaxial surface. The fusion of the three styles and stigmas 

 is complete. The three ovaries are still distinguishable and cor- 

 respond to the three compartments of the compound or syncarpous 

 ovary. The sides of the carpels form the partitions. The axis 

 of the ovary, to which the ovules are attached, is formed by the 

 fused margins of the carpels. The mid-ribs may be seen running 

 down the outside wall, midway between the grooves. 



The ovules enclosed within the compartments have very much 

 the same structure as those of the Buttercup and contain within 

 their nucellus a large cell, the embryo-sac (megaspore) which gives 



