of a Hybrid Digitalis. 273 



condition of any part of this organ in either of the three plants, 

 fn general, a transverse section shewed the fibrous- cells to be 

 arranged in a triple tier (Fig-. 10.). These curious vessels seemed 

 to be set, as it were, upon the sides and edges of void 

 dodecahedral and other polyhedral spaces, as though certain 

 original cells of these shapes had disappeared and left this frame- 

 work of their structure alone standing-. The triple tier is not 

 distinguishable upon looking directly down upon the inner surface 

 of the anther (Fig. 11.), but some of the fibrous-cells may be seen 

 standing upon the junction-edges of the cells of the epidermis, 

 where this membrane has been partially cleaned of the inner 

 coating composed of them. Fig. 12. (A) is the appearance which 

 they assume when detached by digestion in nitric acid : (k) being 

 the cells of the epidermis, (/) an accidental appearance in a 

 grain of pollen recalling somewhat of the character of the grain 

 figured at Plate xvi. Fig. 3. H. 



Structure of the Ovules. Piate xvn. Fig. 13. When the 

 corolla is expanded, the ovules are entirely composed of a con- 

 geries of large vesicles, and their surface has a very remarkable 

 and granulated appearance. At this period of their existence 

 I was unable to detect any thing very precise respecting the 

 distinction and distribution of their several parts. The fora- 

 men (m) however was evidently seated near the hilum, and a 

 darker spot indicated the chalaze (n) to be at the opposite ex- 

 tremity (see also Plate xvin. Figs. 1. and 4.) In the ovules of 

 purpurea and lutea, there is no difficulty in tracing the separate 

 parts of the ordinary structure, if they be examined shortly after 

 their impregnation ; but before their fertility is secured I have not 

 hitherto been able to detect in these plants, more than in the 

 hybrid, any thing but a homogeneous mass of cellular tissue. 



Vol. IV. Part II. Mm 



