1896 THE MICROSCOPE. 5 



the ordinary fixed stage of a microscope. On this is 

 placed the mechanical stage I am about to describe. 



A slip of thick sheet brass, about one thirty-second of 

 an inch thick is taken. It is six inches long and three 

 inches wide. It is also provided with spring clips to hold 

 the object on. It is bent at the two ends so as to make 

 a double stage like a V at each end, leaving aboat a half 

 an inch between the upper and the lower portions. On 

 each v-piece two cuts are made so that on each side a 

 portion is left which is bent up so as to make a spring to 

 bear the stage downwards. Acting against the two 

 pieces are two fine screws fixed in the bent v-shaped part. 

 These screws have large heads to use with the fingers, 

 first the right and then the left. Of course there is a 

 hole about a half of an inch in the centre of the mechan- 

 ical stage to view the object with and opposite the hole 

 in the centre of the fixed stage-proper. 



Now when in use it is placed on the fixed stage. 

 When the object on a slide is placed on it under the 

 spring clips, it can be moved about up or down, trans- 

 versely and from right to left. It can likewise be moved 

 the same way as the objective by the screws and 

 the springs acting against them. It can be entirely 

 removed and the fixed stage used alone. It can also have 

 index marked on it and the fixed stage marked with fif- 

 tieths of an inch up and down and transversely so that 

 the object can be indexed. In fact I think it is simple 

 and cheap and also effective. I wish it could be tried. 



Eggs of Bot Fly. — -The eggs of the hot fly (gasterophilus 

 equi) mounted attached to the hair make very pretty transpar- 

 ent or preferably opaque objects. They may be found in 

 abundance on farms where horses are raised, especially on 

 horses that have long run in the fields. The eggs are deposited 

 on the hairs generally of the forelegs and mane, whence they 

 are taken into the mouth and swallowed. The larva? are 

 hatched in the stomach. 



