12 HOFFMANN ON THE CIRCULATION 



coloured ; they are connected with the compact parenchyma- 

 tous cellular tissue by a lax tissue of delicate prosenchymatous 

 cells, forming an investment around them. When the prepa- 

 ration was dried these were partially torn away, and the vascular 

 bundles hung loose in the tubular cavities thus produced. In 

 longitudinal sections the vascular bundles were seen most di- 

 stinctly of a yellowish colour ; between and beside these the blue 

 streaks and points which indicated the sap-bearing cellular tissue. 

 — Flower : when the epidermis had been removed it was easy to 

 detect the reaction here also, and it was seen uniformly through- 

 out the parenchyma (containing colouring matter) of the petals, 

 while the vessels and the delicate parenchymatous cells accom- 

 panying them remained free. The stamens, conjoined into a 

 tube, in the angles of which two vascular bundles are found, 

 exhibited blue points both at their inner and outer boundaries, 

 while the style lying free in the tube of the filaments was only 

 spotted w ith blue in its outer periphery. The stigma w^as found 

 very uniformly permeated with the salt. 



Dioscorea bulbifera, L. (Dioscoreaceae) . — Within seven days 

 after the watering the salt had already ascended five feet up in 

 the stem. — Root : upon reacting on a longitudinal section the 

 w^hole tuber was found spotted with blue points and streaks ; no 

 colouring occurred in the yellowish- white pieces of vascular 

 bundles, which, composed of striped vessels containing air, were 

 visible here and there, nor in a considerable number of reddish 

 spots which microscopic examination proved to depend upon 

 large drops of yellowish red oil occurring in many of the cells. 

 The blue was seen inside the parenchyma of which the tuber is 

 almost exclusively formed, in the same cells wiiich contained 

 starch. In a cross section of the Stem are seen a number of 

 small and also very large vessels not combined into bundles. 

 The larger are in many places situated at pretty regular di- 

 stances, forming something like a hexagonal figure in the paren- 

 chyma of the stem, while the small are scattered quite irregularly, 

 and often enveloped in a pretty thick coat of elongated cells. 

 Inside the central parenchyma or pith occurred isolated blue 

 points ; the broad woody layer on the contrary was wholly devoid 

 both of these and also of vessels, while by far the greatest mass 

 of the salt had ascended in the elongated cells of the liber and 



