120 LETTER XXXVIT. 



otherwise is free ; it contains three cells, in each of 

 which is one ascending ovule ; has a three-lohed style, 

 and a olandular stiofma at the end of each of the lobes. 



This is all the preparation that is made for the sin- 

 gular fruit, which I have already described as resem- 

 bling an ancient buckler, but which the French com- 

 pare to a little head wearing a broad-brimmed hat, 

 whence they call it porte-chapeau. To bring about the 

 metamoi'phosis from the flower to the ft'uit, the follow- 

 ing changes occur ; the calyx — lobes, petals, and sta- 

 mens drop off, and the branches of the style shrivel 

 up ; this reduces the flower to a roundish centre, sur- 

 rounded by a flat-lobed limb. Then the disk, or limb, 

 grows broader, the ovary swells, both change their ap- 

 pearance, the disk gTows the fastest, the whole hardens 

 and becomes brown, and the porte-chapeau {fig- 6.) is 

 completed. It contains three cells, externally indi- 

 cated by three low ridges, and in each cell there is a 

 flat seed (^fig. 70- The seed contains an erect embryo, 

 with two thin flat cotyledons, placed face to face, and 

 a very short conical radicle {^fig. 8.). 



In considering the value of the characters thus 

 described, as existing in the Christ's-thorn, you are to 

 abstract — 1. the valvate calyx ; 2. the five stamens op- 

 posite the five hooded petals ; 3. the fleshy disk ; and 

 4. the three-celled, half-inferior fruit, with one upright 

 seed in each cell ; and you will have the characteristic 

 features of the Buck-thorn Tribe. This is the more im- 

 portant for you to understand, because the Tribe com- 

 prehends species differing materially, in some respects, 

 from what is found in the Christ's-thorn itself. For in- 



