148 NOTES FOR BEGINNERS IN MICROSCOPY. 



shall be able to plainly see that the dark water between the pieces 

 of tartar is teaming with thousands of bright points moving about. 

 On closely inspecting, we shall see the long Leptotkrix, many 

 kinds of shorter bacteria, and round micrococci, all apparently 

 having a grand outing in a drop of water. 



The half-inch objective is too low a power for the study of 

 bacteria ; but in the manner stated will show ten thousand at a 

 glance, while a high power will show only a very few at a time. 



In using the half-inch and paraboloid on the bacteria, we must 

 not forget that after we have the bacteria in plain view, a very 

 slight movement of the mirror will leave us unable to see them. 

 Hence, the mirror should be moved very slowly while we watch 

 closely in the dark water between the bits of tartar. 



Vinegar Eels.— These litde creatures are very popular with 

 beginners in microscopy, and by the following method they can 

 easily obtain a grand view of them, and one which will remain in 

 focus for months if desired. 



Take a one-dram clear glass vial ; fill it about one quarter full 

 of cider or other vinegar well supplied with eels. Into this drop 

 a silk thread, so that one end rests on the bottom, the other end 

 hanging out of the vial. The thread will cling to the side of the 

 vial from the top to the vinegar, and by capillary attraction keep a 

 film of vinegar along its side. 



To hold the vial on the microscope stage, take a bit of cigar- 

 box or other thin wood, about one and a-half inches wide by two 

 and a-half inches long ; across its centre draw two lines three- 

 eighths of an inch apart. The space between these lines is to be 

 hollowed out to fit the side of the vial ; the hollow space is to be 

 blacked with ink. 



Next to the hollow cut a hole, about three-eighths of an inch 

 wide and five-eighths of an inch long, through the block, the 

 length of the hole to run crosswise of the block. This hole is to 

 allow the light from the sub-stage illuminator to pass through. 

 Then cut a quarter-inch square out of each corner of the block ; 

 now pass a small rubber band under one end of the block, up 

 through the cut corners, thence across the vial groove, and under 

 the opposite end. 



