16 INTRODUCTION. 



58. SUCCULENT PLANTS may be immersed in boiling water before pressing, to 

 hasten their desiccation. 



59. THE LENS, either single, double, or triple, is almost indispensable in the or- 

 dinary pursuits of Morphology or Phy tography. In viewing minute flowers or parts 

 of flowers the use of the lens can not be too highly appreciated. For dissection 

 with the lens, a needle inserted in a handle, a penknife and tweezers are required. 

 The dried flowers of the herbarium need to be thrown into boiling water before 

 dissection. 



60. THE COMPOUND MICROSCOPE is undoubtedly a higher aid in scientific inves- 

 tigation than any other instrument of human invention. It is like the bestowment 

 of a new sense, or the opening of a new world. Through this, almost solely, all 

 our knowledge of the cells, the tissues, growth, fertilization, &c., is derived. The 

 skillful use of this noble instrument is itself an art which it is no part of our plan 

 to explain. For such information the student is referred to the works of Carpenter 

 and Quekett. 



61. ON THE PREPARATION OP BOTANICAL SUBJECTS for examination we remark 

 briefly. The field of view is necessarily small, and only minute portions of objects 

 can be seen at oace. The parts of it are to be brought under inspection success- 

 ively by the movements of the stage. 



62. THE TISSUES OP LEAVES, &c., are best seen by transmitted light. They are 

 to be divided by the razor or scalpel into extremely thin parings or cuttings. Such 

 cuttings may be made by holding the leaf between the two halves of a split cork. 

 They are then made wet and viewed upon glass. The stomata are best seen in the 

 epidermis stripped off; but in the sorrel leaf (Oxalis Violacea) they appejir beauti- 

 fully distinct (678, Fig. 585,) upon the entire leaf. 



63. WOODY TISSUES, &c., may be viewed either as opaque or transparent. Sec- 

 tions and cuttings should be made in all directions, and attached to the glass by 

 water, white of egg, Canada balsam. To obtain the elementary cells separately 

 for inspection, the fragment of wood may be macerated in a few drops of nitric acid 

 added to a grain of chlorate of potassa. Softer structures may be macerated sim- 

 ply in boiling water. 



64. CERTAIN REAGENTS are applied to the softer and more recent tissues to ef- 

 fect such changes in the cell contents, of either color or form, as shall render them 

 visible. Thus sulphuric acid coagulates the primordial utricle ( 639) ; a solution 

 of iodine turns it blue j sugar and nitric acid change it to red. 



