16 HOFFMANN ON THE CIRCULATION 



for in four weeks after the watering, the leaves spontaneously 

 exhibited a deep blue colour at their tips. The plants all died 

 in little more than a month, apparently in consequence of the 

 watering with the ferrocyanide, since they were placed in con- 

 ditions otherwise favourable. 



Tritonia fenestrata, Ker. (Iridaceae). — Within two days after 

 the watering, the salt could be detected in the bulb and in the 

 lower part of the tuft of leaves. The lower part of the bulbous 

 mass (which is the bulb formed the year before, or real tuber) 

 was coloured very deep blue throughout; in the upper bulb (of 

 the current year) it was observed that the parts giving a blue 

 reaction were little scattered points and streaks, which were 

 universally distributed. The microscope showed that those 

 lying in the central part were the elongated cells which sur- 

 round the air-bearing vascular bundles ; in the parenchymatous 

 part of the tuber the blue colour was deepest in the starch- 

 filled, irregular parenchymatous cells of which this structure is 

 composed. The circumstance that in all cases, and especially 

 distinctly here in the longitudinal section, the blue-coloured 

 cells were mostly scattered and only exceptionally formed unin- 

 terruptedly continuous lines, proves that the passage of the sap 

 does not take place uniformly through all parts indifferently, 

 but peculiarly through certain cells, which do not lie all in the 

 same place (parallel to the surface of the sections), but more or 

 less scattered, causing a ramification of the currents of sap often 

 of a very irregular character. 



Allium neapolitanum, Cyr. (Liliaceae). — Not even four weeks 

 after the watering could the presence of the ferrocyanide be de- 

 tected either in the interior of the bulb or in the stem. On 

 the other hand, the outermost dead scale of the bulb was 

 coloured of an uniform blue tint, evidently by accidental imbi- 

 bition of the fluid in contact with it, not only in the cells, but 

 both in the reticularly striped and the true unrollable spiral ves- 

 sels, which, moreover, still here and there displayed air in their 

 interior. 



Canna indica (Cannese). — This plant was growing in the open 

 air and was watered on the l7th of July. In seven days the 

 blue reaction could be readily detected in the stem. This exhibits 

 somewhat the same structure as the Palms in the cross section 



