80 PREPARATION AND MOUNTING 



dry. Amongst the most beautiful and easily prepared of 

 these may be mentioned the petal of the geranium, the 

 cells of which are well defined and amongst the most 

 interesting. 



Sometimes this cuticle is removed by maceration of the 

 leaf in watei or by a quicker method boiling in nitric acid. 

 Perhaps it will be as well to give Mr. Arnold's experience. 

 "A leaf of a rhododendron which had been dry some 

 months, and a freshly- gathered leaf of an azalea, were put into 

 a test-tube, and covered with undiluted nitric acid of com- 

 merce of, I believe, about 1/32 specific gravity ; the tube was 

 held over a spirit-lamp until the acid just boiled, and 

 the contents were then thrown into a basin of cold water. 

 The cuticle of the rhododendron leaf partially separated 

 spontane >usly ; that of the azalea came off without the 

 least difficulty. The whole operation did not occupy more 

 than five minutes. Undoubtedly many leaves, according to 

 their texture, will require different strengths of acid, and 

 longer or shorter periods of boiling." 



Closely connected with the leaves are the ANTHERS and 

 POLLEN, of which a great number are beautiful and interesting 

 subjects for the microscopist. 



The mallow tribe will furnish some exquisite objects, 

 bearing the appearance of masses of costly jewels. These 

 are usually ^dried with pressure, but the natural form may 

 be more accurately preserved by allowing them to dry as 

 they are taken from the flower, with no interference except 

 thoroughly protecting them from all dust. Sometimes the 

 anther is divided, so that the cell required to receive them 

 may be of as little depth as possible. The common mallow 

 is a beautiful object, but I think the lavatera is a better, as 

 it shows the pollen-chambers well, when dried unpressed. 

 The pollen is often set alone, and is well worth the trouble, 

 as it then admits of more close examination. Often it is 

 convenient to have the anther and pollen as seen in nature 

 on one slide, and the pollen alone upon another. The 

 former should be taken from the flowers before their fuil 



