STRUCTURE OF FLOWERS. 



425 



Fig. 229. 



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 Microsco- 

 pist, 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 change of hue which the Chlorophyll 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 

 Geranium (Pelargonium), of which a small portion is represented 

 in Fig. 229. The different portions of this Petal, — when it has 

 been dried after shipping it of its cuticle, immersed for an hour 

 or two in oil of tur- 

 pentine, and then 

 mounted in Canada 

 balsam, — exhibit a 

 most beautiful variety 

 of vivid coloration, 

 which is seen to exist 

 chiefly in the thick- 

 ened partitions of the 

 cells ; whilst the sur- 

 face of each cell pre- 

 sents a very curious 

 opaque spot with nu- 

 merous diverging pro- 

 longations. This me- 

 thod of preparation, 

 however, 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. 229. 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 Spirit- 



> * See especially Mr. Tuffen West ' On some Conditions of the Cell-Wall 

 in the Petals of Flowers,' in " Quart. Journ. of Microsc. Science," Vol. vii. 

 (1859;, p. 22. 



Cells from the Petal of the Geranium 

 (Pelargonium). 



