158 THE MICROSCOPE. Oct. 



PRACTICAL SUGGESTIONS. 



By L. a. WILLSON, 

 cleveland, ohio. 



Indexing Slides. — It is ven' uncomfortable to be unable to 

 find a particular slide when desired. To obviate an incon- 

 venience of this kind it is well to number and index the slide, 

 and also to label the boxes containing the slides with the 

 box. A very little trouble in the direction here indicated will 

 place every slide under control of its owner. Without some 

 arrangement it is remarkable how soon a slide will become as a 

 needle in a hay-stack. Little index books may be pro.^ured 

 and are inexpensive. It is well to keep boxes with trays for 

 slides in course of preparation. la such cases always write the 

 name of the preparation on a slip of ])aper and keep it in the 

 tray with the slide until it is permanently mounted. 



Erysippei. — These are the powdery mill dews and this is 

 the season for finding them on leaves. They are beautiful and 

 compete favorably with diatoms as microscopic objects. Leaves 

 will be found that look as if full of cobwebs or as if they had 

 been whitewashed; — if they belong to this class, when in fu'l 

 fruit, often with the eye or better with a lower power lens, in- 

 numerable little dark dots can be seen scattered through the 

 whitewash or cobwebs on the leaves. 



When the leaves are gathered it is well to press them at once. 



On arriving at the microscope, with a spatula scra2:>e off a few 

 of the dark dots and transfer to a drop of water on a slide cover 

 and examine with a low power. Then remove the slid-*, gently 

 press on the cover with the finger and examine with a higher 

 power about a quarter objective. With the low power the dark 

 dots will be seen to be variously marked periehsia. Around 

 theapothecia will be f )und the appendages by which the genera 

 are classified. Some appendages are simple, some are long sharp 

 spikes, some are shepherd crooks, some are long wth stars at the 

 end. The pressure on the slide will mash the perithecia and 

 expose the asci containing the spores. On the number of spores, 

 specific distinctions are founded. 



It it nice, neat, clean work which any miscoscopist with a 

 little patience can accomplish. The U. S. agricultural depart- 



