142 KEPOET 108, U. S. DEPAETMEXT OF AGEICULTUEE. 



and then placed in alcohol for a few hours before mounting on a slide. Many of the 

 larger mites can be kept in small vials of alcohol and examined in watch glasses; but 

 the smaller mites must be mounted on slides, and many students mount all of their 

 specimens. Various media have been used for mounting mites on slides. Canada 

 balsam has been used more than anything and is very satisfactory for most forms with 

 a chitinous tegument. For the delicate forms many use glycerin jelly, but a mixture 

 of it, 10 parts glycerin jelly to 1 of glacial acetic acid is considered a better medium. 

 Before putting the specimen in balsam or glycerin it is well to clear it by use of a 

 few drops of xylol, oil of cloves, or oil of bergamot. Care should be taken in placing 

 the balsam or glycerin so that the resulting mount will be no thicker than necessary 

 to prevent pressure on the specimen. Instead of keeping specimens in alcohol 

 before mounting them, some prefer a mixtiu-e of 2 parts distilled water and 1 of acetic 

 acid. If mounted in balsam it is not necessary to seal the mount, but if in glycerin 

 it should be ringed with zinc-cement, Brunswick black, asphalt, or some similar 

 material. It is not easy to rear mites in captivity. Some forms, like t5Togl}T)hids, 

 can be placed on a decaying surface, and if the moisture and ventilation is main- 

 tained will breed in enormous numbers. But the Oribatidae and Parasitidae are 

 much more difficult. These can be kept within a small glass cell placed on a micro- 

 scope slide and covered with cover glass held down by a few drops of glue, or a rubber 

 band. Cells can be purchased, or made by cutting off sections of glass tubing of the 

 proper size. A piece of moist blotting paper may be put in the cell, and then the 

 mites or eggs and some food. It is necessary to see that the cell does not dry out 

 nor become too moldy. By care many mites can be reared in such cells and their 

 habits and transformations observed under the microscope. Ticks may be reared 

 by placing them on a suitable animal and covering the spot with a cloth or muslin 

 bag to catch the tick when ready to molt. The rearing of species parasitic on birds 

 would be difficult and has not been accomplished; but those on some of the domestic 

 birds doubtless could be studied by isolating a pair on a host in confinement. 



