BURGESS : PIGMENT CELLS OF PLANTS. 



59 



Colour, will be the common field poppy, Papaver Mhoeas. Here we have 

 a simple red film witli raised venations running in almost parallel lines, 

 slightly narrowed ; at each end the length of these cells I find by mea- 

 surement to be one eighty- seventh of a millemetre in width, and about 

 one-ninth of a millemetre in length, average mean of several different 

 cells — here again, we have no central nucleus — but a plain network-like 

 form of cells in form somewhat to be compared to an elongated parallel- 

 ogram slightly com]3ressed at both ends.* The wall cells here present a 

 little variety, they appear on close inspection with the lower powers to be 

 like several veins piled one upon another in a slightly serpentine form, 

 but with the higher powers, one-eighth for example, the top has some- 

 what the appearance of the links of a chain cable — this latter appearance 

 perhaps requires further observation before it is to be fully accepted as a 

 matter of fact. 



Division III. 



Cells Singular in Form and Beautiful in Colour. 

 This division I shall illustrate by two examples, both taken from 

 plants the petals of which to the eye present a velvety appearance. The 

 first is the pansy, Viola tricolor , here, viewed simply in its flat form, by 

 transmitted light the appearance is, cells of a roundish ovate form, 

 inclining to the hexagonal, of one- seventeenth of a millemetre long, and 

 one-twentythird of a millemetre wide. The cell walls are very much in 

 appearance like the Pelargonium only more clearly defined — hollow and 

 filled with dark colouring matter (this petal of course was one of a dark 

 colour, had it been a light one, the pigment cells would have been filled 

 with a light coloured fluid) around the top edge of this wall I counted so 

 many as nineteen and twenty clear wart-like protuberances of a transpa- 

 rent, or semi-transparent nature, not inclining inwards as in the Pelar- 

 gonium, but as nearly as possible uniformly distributed at equal 

 distances along, or around the cells ; in the centre of these walls, a 

 nucleus is seen, having many lines radiating in all directions, towards 

 the walls of the cells, and if our observations went no further, our des- 

 cription would be at an end, after stating both surfaces were very much 

 alike. But, taking our cuticle in section, we now see in regular order, 

 one continued row of pyramid-shaped bodies having a coloured apex, in 

 which is seen a coloured fluid, and from this point streaming downwards, 



* The narrower ends of tlie cells as compared with, the centre width, is in the pro« 

 portion that one hears to three. 



