STRUCTUEE OF PARTS OF FLOWER. 



895 



seems to answer best, provided the cell bo air-tight, and the 

 specimen fresh. 



251. Structure of Flowers. — Many of the smaller Flowers are, 

 when looked at entire, with a low magnifying power, very 

 striking Microscopic objects ; and the interest of the young in 

 such observations can scarcely be better excited, than by directing 

 their attention to the new view they thus acquire of the " compo- 

 site" nature of the humble down-trodden Daisy, or to the beauty 

 of the minute blossoms of many of those Umbelliferous plants, 

 which are commonly regarded only as rank weeds. The scientific 

 Microscopist, however, looks more to the organization of the 

 separate parts of the flower ; and among these he finds abundant 

 sources of gratification, not merely to his love of knowledge, 

 but also to his taste for the beautiful. The general structure of 

 the Sepals and Petals ■which, constitute the "perianth" or "floral 

 envelopes," closely corresponds with that of leaves ; the chief 

 difference lying in the peculiar changes of hue which the chlo- 

 rophyll almost invariably undergoes in the latter class of organs, 

 and very frequently in the former also. There are some petals, 

 however, whose cells exhibit very interesting peculiarities, either 

 of form or marking, in addition to their distinctive coloration ; 

 such are those of the Greranium (Pelargonium), of which a small 

 portion is represented in Fig. 188. The different portions of 

 the petal, — when it has been 

 dried after stripping it of its Fig. i88. 



cuticle, immersed for an hour 

 or two in oil of turpentine, 

 and then mounted in Canada 

 balsam, — exhibit a most beau- 

 tiful variety of vivid colora- 

 tion,- which is seen to exist 

 chiefly in the thickened par- 

 titions of the cells ; whilst 

 the surface of each cell pre- 

 sents a very curious opaque 

 spot with numerous diverging 

 prolongations, which looks as 

 if formed by a deposit of 



sclerogen upon its interior. This method of preparation, how- 

 ever, does not give a true idea of the structure of the cells ; for 

 each of them has a peculiar mammillary protuberance, the base 

 of which is surrounded by hairs ; and this it is which gives the 

 velvety appearance to the surface of the petal, and which, when 

 altered by drying and compression, occasions the peculiar spots 

 represented in Fig. 188. The real character may be brought 

 into view by Dr. Inman's method ; which consists in drying the 

 petal (when stripped of its cuticle) on a slip of glass, to which it 

 adheres, and then placing on it a little Canada balsam diluted 

 with turpentine, which is to be boiled for an instant over the 



Cells from the Petal of the Geranium {Pdargtmium). 



