MICKOSCOriCAL COLLECTIONS IN FLORIDA. 133 



ing out as the flowers expand. The leaves of this plant are 

 thickly studded on hoth sides with stiff transparent hairs, lying 

 nearly flat on the surface, and all pointing towards the tip end of 

 the leaf. At the base of each hair is a cluster of glandular cells, 

 amounting sometimes to fifty or more, arranged in beautiful 

 geometrical forms. When pressed and dried in the herbarium, the 

 body of the leaf turns to a dark green, almost black, and on this 

 back-ground, with a half-inch objective, the hairs stand out like 

 sculptured glass, and the glands like mosaics of purest pearls. I 

 think it is the most attractive opaque object that can be shown 

 under the microscope. 



That these glandular cells, covering as they do nearly half the 

 surface of the leaves, especially the upper surface, and differing 

 from all other vegetable cells, subserve an important purpose in 

 the sustenance of the plant, there cannot be a doubt ; but just 

 what that purpose is, or at least what is the mode of operation, I . 

 think, has never been ascertained. 



In the same locality will very likely be found the most beauti- 

 ful of all the Croton plants, the C. argyranthemum. Unlike 

 the other Crotons, which are bushes, this is an herb growing 

 only about a foot high, with a milky sap which exudes when the 

 stem is broken. The leaves are silvery, verging in some cases to 

 a bronze color, and are thickly covered on the upper side with 

 most remarkable and beautiful stellate scales. The flower-buds 

 and stems when pressed, make much more beautiful opaque 

 objects than the leaves. 



The object of these scales is, without doubt, to prevent the 

 too rapid evaporation of the moisture stored up in the plant. . 

 They are the exquisitely woven blankets which preserve the 

 precious juices so laboriously gathered. The same kind of cov- 

 ering is spread over the leaves and stems of all the air-plants of 

 Florida, and doubtless for the same purpose. The well-known 

 Florida moss, although not a moss, but a member of the pine- 

 apple family, (Tillandsia usneoides), is an exceedingly beautiful 

 object under the microscope. Each hanging stem is overlaid 

 with filmy white scales, every one of which is fastened in its 

 place by what w r ould seern to be the stamp of some miniature 



