BURGESS : PIGMENT CELLS OF PLANTS. 



55 



— and therefore the plan I pursue is as follows : — so soon as I have partially 

 stripped off the cnticle, say about haK way, I take a glass slip made perfectly 

 clean and with both hands take the petal and place it in its partially divided 

 state, resembling the letter Y inverted, on the slip ; each end of the petal now 

 is held tightly down on the slip by means of the two thumbs and carefully 

 pulled in opposite directions, the result is, the filmy cuticle spreads itself 

 gently over the slip and by means of a camel's hair pencil or the thumb, can 

 be laid perfectly flat, and is ready for examination. Tliis when perfectly 

 dry can be covered with a piece of thin glass and so be preserved, or what is 

 better a drop of Canada Balsam can be placed on the cuticle, and by means 

 of a spirit lamp be thoroughly heated and a thin glass cover placed over the 

 whole, and when finished off we have a permanently mounted slide of great 

 beauty. We will assume that the film taken off was the upper 

 surface of the petal, we now see a perfectly white surface immediately under 

 the part stripped off, and turning the petal over, we next observe another 

 coloured surface at the back, by which we learn the petal is composed of tliree 

 distinct and separate cuticles, or perhaps more correctly speaking, a cuticle 

 on each side, divided by an interstratum of cellular matter ; in one petal of the 

 Cactus family which I had thus divided, I observed in the cellular matter 

 occupying the inner part of the petal, several spiral fibres clearly showing 

 the nature of this part of the petal, and the use of the same, in contradis- 

 tinction to the Pigment cells on either side. The next process to adopt is to 

 take a petal precisely like the first, from the same part of the flower, and 

 laying it with its under surface upwards, proceed as in the first instance ; if 

 successful, you have now both sets of Pigment cells. I prefer taking the 

 upper surface from one petal, and under surface from another, as being in 

 practice much more easily done than taking both cuticles from one petalj 

 which is often I find almost an impossibility to do, and in some special cases 

 I have not been able to succeed at all. It will now I trust be obvious 

 that to correctly examine " Pigment cells" under the microscope, we must 

 not take the entire petal and mount it in the state we find it, but that it 

 must be separated into its several parts, each part being taken in detail. 



An interesting question arises here ; there are Botanists who are of 

 opinion that the petals and flowers of plants are only another state of the 

 green leaf, turned by a process of nature in another direction, and others 

 again who maintain that a flower is a flower, altogether distinct from leaves 

 and so forth. To those of our friends (if there be any) who are engaged in 

 the study of Morphology," as this part of vegetable physiology is called, 



