162 sh6rt notes. 



Gay's specimens, to have had an excellent knowledge of the genus. — 

 J, G. Baker. 



Unger's Experiments on Sap-Movement. — In the review of 

 the English edition of ' How Crops Grow,' contained in the first 

 number of the present volume (Journ. of Bot. Vol. VIII. pp. 43-45), 

 objection is made to Unger's experiments with white Hyacinths, being 

 adduced in support of Herbert Spencer's view, that the nutrient fluids 

 in plants ascend mainly by the vessels. The discordance between 

 their results is more apparent than real, though this could not be 

 pointed out in the book itself from want of space. Unger found that 

 when white Hyacinths were watered with the diluted juice of the fruits 

 of Phytolacca decandra, the course of the fibro-vascular bundles was 

 marked out in red from the absorption of the colouring matter. On 

 examining the bundles themselves, the colour was found to be confined 

 to the wood-cells, and the vessels were destitute of it. Herbert 

 Spencer's experiments gave precisely the same result, as will be seen 

 from the following quotation from his paper: — 



" On making longitudinal sections of the part traversed by it, the 

 dye is found to have penetrated extensive tracts of the woody tissue ; 

 and on making transverse sections, the openings of the ducts appear as 

 empty spaces in the midst of a deeply coloured pro senchy ma. It would 

 thus seem that the liquid is carried up tlie denser parts of the vascular 

 bundles ; neglecting the cambium layer ; neglecting the central pith, 

 and neglecting the spiral vessels of the medullary sheath. Apparently 

 the substance of the wood has formed the readiest channel." ('Prin- 

 ciples of Biology,' vol. ii. p. 538.) 



Unger at once arrived at the conclusion that the wood-cells were 

 alone coloured, because they were tlie only channel which the colouring 

 fluid took ; but Herbert Spencer, on comparing a transverse section of 

 the part which the dye had but just reached with one of the lower part 

 in which the dye had remained longest, thought there was ground for 

 believing that the dye had passed up by the diicts and had oozed out 

 of these into the surrounding prosenchyma, the coloration of the sur- 

 rounding tissue being so much greater in the latter case than in tlie 

 former. The experiments which led one observer to attribute the 

 ascent of the coloured fluid to the wood-cells, and the other to attribute 

 it to the vessels, were thus precisely similar ; the only diff"erence con- 

 sisted in the mode in which they were interpreted. The old experi- 



