OF SAP IN PLANTS. 11 



instance, since a strong influx of sap and an active vegetation 

 do not exist in the ovary and the ovules until they are fully 

 developed. In the flower- bud of a blossom unfolded on the 

 same day, the reaction could be detected in the petals, the 

 stamens and in the pistil up to the stigma. The root : this is 

 placed underneath the bulb, and is of a swollen conical form. 

 Internally it is homogeneous, and in the centre is found the 

 bundle of striped vessels ; the blue colour was seen to a slight 

 extent surrounding this, but much more marked at the peri- 

 pherical layer. Bulb : it consists of the bases of some six stems, 

 enveloped by the sheaths at the bases of leaves ; the vascular 

 bundles are scattered irregularly in the former; no reaction 

 could be detected in the bases of the stems. Inside the bulb- 

 scales the vascular bundles lie at some distance from each other 

 in the median layer, while the reaction brought out a great 

 number of blue spots, both in the mesophyllum and, more espe- 

 cially, beneath the inner and outer epidermis of the bulb-scales. 

 In the outermost coats of the bulb the blue colour was not 

 limited to isolated points, but diffused uniformly throughout the 

 entire mesophyllum, with the exception of the vessels. Micro- 

 scopical examination of longitudinal sections showed that the 

 vessels contained air and were uncoloured, while the cellular 

 tissue and especially a portion of the elongated laxer cells were 

 coloured deep blue. It is remarkable that only a portion and 

 not the whole of the elongated vessels were concerned in the first 

 conveyance of the sap. In longitudinal sections it was seen that 

 these cells were much more easily separated from each other 

 laterally than at their ends, by pressure, which seems not unim- 

 portant in reference to the conveyance of the sap. Stem : in a 

 cross section half-way between two nodes, the reaction made 

 visible a large number of blue points, both inside the cortical 

 layer and in the layers of the central parenchyma. The cortical 

 layer is composed of few, narrow, striped vessels, liber bundles 

 with very long cells colourless as glass, and of elongated cells 

 which were in part coloured blue ; the layer allied to liber found 

 at the circumference of the central parenchymatous substance 

 of the stem, which is very thick in the internodes, while it is far 

 weaker at the nodes, did not become coloured. The vascular 

 bundles are scattered in the internal substance and were not 



