BURGESS : PIGMENT CELLS OF PLANTS. 



57 



are not straight (like cells of the honey comb) but assume the general 

 appearance of a six sided figure — the size of these cells I found to be, 

 taking the mean (or average) of four distinct cells selected as affording a 

 good sample of the rest, one-twentieth of a millemetre long, and one- 

 fourteenth of a millemetre wide, in some cases the width and breadth 

 were about equal ; in the centre of this there was a dark nucleus, with 

 thirty-one lines (mean number,) radiating towards the cell walls aroundit, — 

 this nucleus has been by some called the stoma of the petal. This 

 view I do not endorse, I am rather inclined to form an opinion that it is 

 the reservoir for colour or perfume (among other purposes) or even both. 

 This nucleus presents the general appearance of an insect with many legs 

 around it, lying on its back. The wall cells around this nucleus, how- 

 ever, are the great seat of colour — they are hollow vein-like processes, 

 filled with a colouring matter ; on these side veins by close examination, 

 under an eighth may plainly be seen a number of spine like forms (Dr. 

 Carpenter calls them hairs,) hollow and filled with colour ; these incline 

 inwards, somewhat like the teeth in the peristome" of some of the 

 mosses ; these are not observed, however, with the lower powers. I 

 noticed sixteen or seventeen of these " teeth" or haii's in several of these 

 cells. 



From another petal of a deep crimson colour, I obtained very 

 different results ; here the cells were one-twentieth of a millemetre long, 

 and only one-tenth of a millemetre wide, in proportion only one half of the 

 length in width, here again, the nucleus contained seventy-eight 

 lines and eighty-six lines respectively in two cases where I counted, 

 radiating from it, the nucleus also was more elongated than in the other 

 case. For perfect examination, it is best I find, to have some petals put 

 up dry, and some in Balsam, as each way admits of different kinds of 

 observation being carried on with advantage, which cannot be found 

 when the pigment cells are prepared in one way only. 



An interesting question arises here which would afford matter for 

 observation and discussion ; this coloured fluid, how is it elaborated ? — 

 What is its special use ? — For it is surely useful as well as ornamental. 

 Again is it secretory, excretory, or circulatory ? I raiher lean to the idea 

 of it being a secretion, having circulation confined within given limits. 



Division II. 

 Cells Simple in Form or Colour. 



To illustrate this we will take the common buttercup. Ranunculus 

 No. 53, September 1. E 



