1895 THE MICROSCOPE. 19 



of crawling. They attach themselves by the head, 

 shorten and broaden the body and draw in the foot. 

 Then fastening themselves by the foot again, they elon- 

 gate the body to its full extent and repeat the process. 

 The body of the Rotifer is so transparent that the action 

 of the mastax and the motion of the food in the body 

 can be seen with a high power instrument and with this 

 instrument the movement of the water in the body can 

 be seen. 



These animals are said to produce three kinds of eggs, 

 a male, a female, and a kind that can be dried up and re- 

 main for a long time, and then under favorable condi- 

 tions they may hatch. It has been proven that these 

 eggs sometimes float in the air. If the water in which 

 the Rotifer lives, dries up very slowly, the animal rolls 

 itself into a ball, covers itself with a gelatinous substance 

 which hardens aud retains suflBcient moisture to keep the 

 animal alive for a long time. Under favorable conditions 

 it becomes active again. 



XXI. — Vinegar Eels. 



Some pure cider vinegar which has stood for a long 

 time will probably contain the Anguillulae aciti, or vine- 

 gar eels. With a little pipette, such as is used for drop- 

 ping medicine, carefully take from the bottom of the 

 vessel a little of the vinegar and place one drop in the 

 center of the flat side of the stage, being sure to have 

 the glass perfectly dry, or otherwise the liquid will 

 spread over the glass and not be of sufficient depth. 

 Place the two largest lenses together, arrange the mirror 

 to show a bright field and focus carefully. Some small 

 thread-like bodies will probably be seen wriggling about 

 actively. These are the vinegar eels. Fig. 4. With the 

 two lenses they appear to be from 5 to ^ inch in length, 

 but with the three together, a large one will appear to 

 be from 1 in. to Ik inches in length. Look at one that is 



