OF SAP IN PLANTS. 39 



the solution had penetrated into several of the large and small 

 spiral vessels of the stem, and still more had ascended in the 

 delicate parenchymatous tissue surrounding the vascular bun- 

 dles ; the pith and remaining portions of the cellular tissue had 

 taken no part. When the lower end of a fragment of a balsam 

 stem 3 inches long was dipped in ink and the upper end sucked, 

 the ink rose instantaneously. From this is evident how consi- 

 derable an obstacle the uninjured epithelium of the root opposed 

 to the forced penetration of the fluid in the preceding case. 



Balsamina hortensis. — The plant was allowed to stand dry 

 from the 14th to the 19th of June, until the withering stem had 

 collapsed considerably. The soil was then well watered with 

 14 cubic inches of dilute solution of the ferrocyanide, which was 

 wholly retained by the mould, as in a sponge (the plant stood 

 in a pot 5 inches high and 4 inches in diameter). On the 21st 

 it began to wither, the leaves exhibited spots and died, while 

 the stem was still partly elastic. On the 23rd the plant was 

 analysed. All parts had absorbed. In the cellular tissue of the 

 pith and rind, the i7itercellular spaces or passages, especially, 

 were found deep blue, so that the rind-cells which contained a 

 red sap, presented red spots enclosed in blue frames; in the 

 pith the whole of the cell-contents were coloured blue in many 

 places. The vessels, striped as well as unroUable spirals, to- 

 gether with the immediately adjacent prosenchyma, w^ere almost 

 without exception dyed deep blue ; air-bubbles were met with in 

 very few, but sometimes even in those vessels which contained 

 blue fluid. 



b. Retarded absorption of the Fluid. 



Oxalis tetraphylla, — Watered very slightly with the saline 

 solution from June 25th to July 27th ; the plant was exposed to 

 the atmospheric moisture in the open air. About this time the 

 leaves began to lose their colour and wither. — Analysis. The 

 bulb is composed of two distinctly separated circles of scales, 

 from the interior of which springs the leaf-stalk. The solution 

 was principally met with in the periphery of the inner portion 

 of the bulb ; and the elongated cells at the surface of the separate 

 fleshy scales, but not the spiroids, had also absorbed it in very 

 small quantity. — Leaf-stalk. This contained a loose circle of 



