126 THE MICROSCOPE. 



the mass is crvstalized. Beautiful crystals suitable for an inch 

 objective will be formed. 



A Method of Mounting Peritheciaof Erysiphe. — Remove 

 the perithecia with a spatula and place them in the center of 

 the slide. Cover them with hydrate of potash and let them soak 

 for a few minutes. Then press them with a cover-glass and 

 partially squeeze out the asci. Wash out the potash solution 

 with a few drops of alcohol. Then flood with eosin. Wash out 

 the eosin with sufficient alcohol. Then mount in benzole 

 balsam. You will have a beautiful slide showing anceptacles, 

 asci and spores. The spores will take the deepest stain and 

 will stand out prominently. 



Flower Crystals of Sugar. — Prepare two test tubes of sat- 

 urated solution of sugar; one of alcohol, the other of water. 

 Then mix the two solutions in a third test-tube, and when 

 throughly mixed, place a drop in the center of a slide and 

 let it rest until it becomes a hard homogeneous ma«s 

 Then set this slide, thus prepared, on the top of a stud- 

 ent's lamp shade. In the course of a short time, the flower 

 crystals begin to develope. Leave the slide in that position un- 

 til crystals have developed over the whole mass. The crystals 

 are now very hard and permanent and may be mounted. View 

 it with the polariscope. 



Demodex folliculorum. — This is a parasite of the cebace- 

 ous sacs and of the hair follicles of the human skin, and is found 

 on some of the lower animals, being the cause of mange in dogs. 

 It is also called Acarus folliculorum , and Entozoon folliculorum. 



Remove a little of the cerement, place it upon a slide, put a 

 drop of castor-oil or of olive-oil on it, tease well with needles, 

 cover with thin cover and examine with a quarter-inch objective. 

 The parasite, which varies in length from 1-50 to 1-100 of an 

 inch in length can then be easily seen, ofcen alive. This para- 

 site is the true Acarus, and has the typical number of eight legs; 

 its abdomen is finely striated. They can be mounted by run- 

 ning a ring around the cover after being prepared as above di- 

 rected. When mounted in glycerine, it shrinks up and become 



