1642 Journal of Applied Microscopy 



only with a very clean, soft, cotton cloth or with lens paper. They must be kept 

 scrupulously clean. The student should learn the different combinations of low 

 and high powers immediately and how to change from one to the other without 

 difficulty. In the directions, the | objective with either eyepiece will be called 

 the low power, and the i objective with either eyepiece the high power. 



The wiping rags should always be clean, and the slides and cover-glasses 

 must be kept scrupulously clean. The student should learn at the beginning 

 how to clean the cover-glasses without breaking them. To do this, take the 

 cover-glass, moistened in water or alcohol, in the rag between the thumb and 

 forefinger and hold it at the edges between the thumb and forefinger of the other 

 hand. In making a mount air bubbles are to be avoided. To accomplish this, 

 after the object has been placed on the slide and covered with a drop of water, 

 hold the cover-glass at the edges between the thumb and forefinger and bring it 

 down obliquely onto a needle held in the other hand, and then withdraw the 

 needle gradually. The cover-glaes will then settle down on the object sur- 

 rounded by water. No water or other reagent must be on top of the cover-glass. 

 If too much water has been put on the slide it may be removed with blotting 

 paper. If the study of a good specimen cannot be finished in the given time, it 

 may be preserved for a number of days by running a little fifty per cent, glycerin 

 under the cover-glass. This will of course kill any living organism. Reagents 

 cost money, and are not to be poured out like water. The same is true of the 

 material for study. This is often difficult to obtain and should be used with 

 economy, and all good surplus material returned to the receptacle from which it 

 was obtained. 



All objects studied are to be carefully figured and described. The drawings 

 may be outlined with the 3H pencil and then finished with the 6H. If time is 

 at hand, the drawings may be finished in India ink with a fine drawing pen. 

 Learn how to keep the pencils sharpened to a fine point. After sharpening with 

 the knife rub the point smooth on a piece of paper. The drawings are to be 

 placed only on the front side of the drawing paper. The notes may be written 

 continuously on both sides of the note paper, but are always to be taken down 

 in ink. The plates containing the drawings should be numbered in Roman 

 figures at the top, and the name of the plant or object written at the bottom. 

 The separate drawings on the plate may be numbered in Arabic figures, and a 

 proper record of them is to be kept in the notes. The notes on each plant may 

 be numbered the same as the plate containing the drawings to illustrate it. The 

 drawings should not be crowded, and the number should always be written below. 



The diameter of the field (the white disc visible when looking into the micro- 

 scope) is about six to eight inches when projected onto the table. Learn to do 

 this by looking with one eye on the table beside the microscope and with the 

 other into the tube. In this way the magnified image may be directly measured. 

 The actual diameter of the area covered can easily be determined for the low 

 powers by examining a millimeter rule. It is about 2y'^|j mm. for the f objective 

 and |- ocular combination, and -^ mm. for the ^ objective and f ocular combi- 

 nation. Learn to keep both eyes open when taking only ordinary observations 

 in the microscope. Be sure to use both eyes, else one will be trained for more 



