390 APPENDIX 



solution by dissolving five grams of potassium hydrox- 

 ide in ninety -five cubic centimetres of distilled water. 

 Keep potasb solutions in bottles witb ground-glass stop- 

 pers, and smear the latter witb vaseline to prevent them 

 from becoming fastened in tbe necks of the bottles. 



34. Reagent Bottles. 



Each table should be supplied with at least one set of 

 the common reagents and stains, put up in bottles hold- 

 ing two or more ounces, according to the number of stu- 

 dents working at the table. If the bottles be circular 

 they may be set into a tray made by boring holes of the 

 required diameter in a piece of plank an inch or more in 

 thickness. The tray will avoid the necessity of a set of 

 shelves, which is often in the way, and will keep the 

 bottles in a compact space. Each bottle may be closed 

 by a bulb stopper which carries a glass pipette and 

 serves at the same time for a dropper. These " Stand- 

 ard Medicine Droppers " come in boxes containing one 

 dozen each, and may be obtained of J. J. Requa, New 

 York. Each bottle should also have a label, giving the 

 name, composition, and use of its contents. 



35. Sachs's Food Solution for Green Plants. 



Use. — A culture-medium for green plants. 

 Preparation. 



Distilled water .... . 1000 cubic centimetres 



Potassium nitrate . . 



Sodium chloride (common salt) . 

 Calcium sulphate (gypsum) . . 

 Magnesium sulphate .... 

 Calcium phosphate (pulverized) . 



1 gram 

 0.5 " 

 0.5 " 

 0.5 " 

 0.5 " 



To the above mixture add five or six drops of a weak 

 solution of chloride of iron. 



36. Salt Solutions. 



Use. — The strong solutions are used as plasmolyzing 

 agents ; the weak, to form a neutral medium in which 



