of a Hybrid Digitalis. 271 



over the whole surface of the placenta. It is very difficult how- 

 ever to be quite certain of this fact, and I may be wrong; but 

 after numerous dissections made upon the three plants, I found 

 I could generally raise, with the point of a very fine needle, a 

 thin gelatinous film of a delicate fibrous structure from between 

 the ovules Fig. 4. (<?'), which film seemed to be similarly con- 

 stituted, and also continuous with the stigmatic tissue (e). 



Cellular tissue of the Pistil. These cells are for the most part 

 compressed into tolerably regular rhomboidal dodecahedrons, ex- 

 cepting in the placenta, where, as the ovarium increases, the vesicles 

 assume that irregular character so well described and represented 

 by Mons. A. Brogniart in the parenchyma of the leaf, (Ann. des 

 Sc. Vol. xxi.) and they have the same sort of interstices filled with 

 air between them as those which occur in that organ. When 

 the style is digested in nitric acid, the separate vesicles of its 

 cellular tissue become cylindric-oval, Fig. 5. (o) : and I have repre- 

 sented an appearance (p) which was noticed several times upon 

 some of these vesicles, of a faintly marked band running down 

 one side. — Further examination may perhaps throw some ad- 

 ditional light upon this circumstance, but at present I know not 

 to what cause it may be ascribed. 



Epidermis of the Floral Organs. Plate xvn. Fig. 6, 7. The 

 flattened cells are of the same size in the three plants, their 

 diameter being somewhat more than the thousandth of an inch. 

 They vary in shape from hexagonal to quadrangular prisms 

 bordered by straight, or waved sides. This membrane is irregu- 

 larly supplied with stomata (/). When digested in nitric acid, 

 the cells assume an appearance represented in Fig. 7., as though 

 the granular matter they contain were coagulated into a nucleus, or 

 else were enclosed in a separate internal vesicle. Whether this 



