PROCURING OBJECTS. 79 



and is distinct from those surrounding it. It can be observed 

 in all plants in which the circulating fluid contains particles of 

 a different refractive power or intensity, and the cellules are of 

 sufficient size and transparency. Hence all lactescent plants, 

 or those having a milky juice, with the other conditions, ex- 

 hibit this phenomenon. The following aquatic plants are 

 generally transparent enough to show the circulation in every 

 part of them : Nitella ~kyalina y Nitella translucens, Chara 

 vulgaris, and Caulinia fragilis. In the Frogbit (Hydrocharis), 

 it is best seen in the scales surrounding the leaf-buds, with a 

 power between 60 and 200 diameters. 



The jointed hairs of the filament of the anther in Trandes- 

 cantia Virginica (Spiderwort) ; the delicate hairs on the leaf- 

 stalk of Senecio vulgaris (Groundsel) ; and a section of the 

 leaf of Vallisneria spiraliSj will show the circulation, especially 

 when viewed with a high power. 



For the following recapitulatory list of plants, which may be 

 used in microscopic examinations, the author is indebted to 

 Balfour's Class Book of Botany, Edinburg, 1852. 



1. Cells and Cellular Tissue. Sea-weeds; rice-paper; inde- 

 pendent cells with nuclei, in yeast plant (Torula Cerevisias) ; 

 cells with nuclei and nucleoli in ripe fruit of strawberry, in the 

 onion bulb, and in ovules or very young seeds; cells united in 

 a linear series in common mould, conferva, and many hairs ; 

 branching cells in many hairs, and in some moulds, as 

 Botrytis; cells united in fours in pollen of Acacia, and in some 

 species of sea-weeds ; cells thickened by deposit of lignin, in the 

 shell of the Cocoanut, and Attalea funifera or Piacaba palm, in 

 the stone of the peach, cherry, and nut, in the seed of the 

 Ivory palm and Date, in the gritty matter of the Pear; cells 

 with siliceous covering in Diatomacese. Porous cells in Elder 

 pith, in stem of common garden Balsam (Balsamina horten- 

 sis), in the outer covering of the seeds of Gourd and Almond, 



