20 HOFFMANN ON THE CIRCULATION 



wood-vessels. In the interior of the petiole the absorption of 

 the sap was indicated only by a few spots becoming blue. 



Aloe picta, D.C. (Liliaceae). — Not even after five weeks, any 

 more than at several shorter periods, could I detect the slightest 

 trace of the salt in the roots, buds, stem or leaves of these 

 plants, which were perfectly healthy, and which scarcely betrayed 

 any injury even at the point of the main root in consequence of the 

 watering. It is true the application of the salt of iron to a cross 

 section discoloured the yellow fluid (the aloe-bitter) which ex- 

 uded, transparent, from the large, very much elongated cells 

 near the spiral vessels at the whole periphery of the leaf, but the 

 stain was brownish black, not blue ; a reaction which occurred 

 also with Aloes of this species never watered with the ferro- 

 cyanide, and which therefore must be attributed to tannic acid. 

 The absence of absorption after the stated period is the less re- 

 markable, since these plants remain for seven months of every 

 year in a dry part of the conservatory, without ever being 

 watered, therefore without requiring any other fluid than that 

 which they receive through evaporation when other plants are 

 watered. 



Zephyranthes grandiflora, Lindley (Amaryllidaceae). — Three 

 days after the watering no reaction could be detected in the 

 bulb, petals, or ovules ; four days later, however, the bulbs ex- 

 hibited distinct blue spots both in their outer and also in their 

 inner scales, but the yellowish vascular bundles were not stained. 

 The different lamellae of the bulb consist here of two epidermal 

 surfaces, of parenchyma-cells full of starch, of elongated cells 

 which are very soft and loose, and especially contained the blue 

 fluid, and next to these, in the median line, of imroUable spiral 

 and annular vessels, surrounded by a few delicate prosenchy- 

 matous cells, as is usual in herbaceous plants. At this period 

 no salt had penetrated into the stem, not even into the lowest 

 part next the bulb. The plants in the same pot all died within 

 eleven days. 



Cyperus monandms, Roth (Cyperaceae). — Nine days after the 

 watering the ferrocyanide was found in the stem and branches. 

 The rhizome, which was dug up after thirteen days, was, like 

 the whole plant, perfectly stiff and healthy, as was the case with 



