16 INTRODUCTION. 



53. Succulent plants may bo 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 beforo 

 dissection. 



— GO. TriE 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 tho 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 work3 of Carpenter 

 and Quekett. 



61. On the preparation of botanical subjects for examination we remark 

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

 can be seen at o.ice. The part3 of it are to be brought under inspection success- 

 ively by the movements of tho stage. 



r 62. The tissues of leaves, &c, are best seen by transmitted light. They are 

 to be divided by the razor or scalpel into extremely thin parings or cuttiug3. Such 

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

 They are then made wet and viewed upon glas3. The stomata are best seen in the 

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

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



63. Woody tissues, &c, may be viewed either as opaque or transparent. Sec- 

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

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

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

 added to a grain of chlorate of potassa. Softer structures may bo maoerated eim- 

 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 tho primordial utricle (§ 639) ; a solution 

 of iodine turns it blue ; sugar and nitrie acid change it to red. 



