VIII.] 



MINUTE STRUCTURE. 



understand this you must first acquire a correct know- 

 ledge of the minute composition of the various organs. 

 Now, their minute composition is, generally speaking, 

 so simple, that you need find no difficulty in compre- 

 hending it as to general features ; but the parts of which 

 I have to speak which build up the -leaves, and stem, 

 and root are so very minute, that unless you make use 

 of a microscope that will magnify, say, 40 to 80 dia- 

 meters, you will be unable satisfactorily to see the parts 

 which compose these organs. In order to meet this 

 difficulty, in case you cannot get a sight of the objects 

 themselves, which is always best, refer to the cuts, which 

 correctly represent all that is necessary. 



2. Take first, if you please, a very little morsel of 

 Rhubarb out of a tart or jar of stewed or preserved 

 Rhubarb will do very well. It is better that it should be 

 cooked, because then it is soft enough to be torn or dis- 

 sected out with needles. If you have no Ehubarb at 

 hand, a bit, as large as a small pea, of any soft, herba- 

 ceous plant will do. Rhubarb is particularly well suited, 

 because the parts which I wish you to examine are not 

 quite so minute in its succulent rapidly-growing leaf- 

 stalks as they are in plants generally. 



We will suppose that you have taken a very small 

 morsel of boiled Rhubarb. You observe that it is quite 



FIG. 64. Cellular tissue from the petiole of Rhubarb, magnified. 



soft and pulpy, and that a few fibrous strings appear to 

 be mixed up through it. Take a little of the pulp on the 



