ROTIFERS. 131 



the water ; and so we find them masked with a forest 

 of Epistylis,]\ist as marine crabs often are with sertula- 

 rians. The free-swimming rotifers are very active in 

 their habits, although we may witness them as long 

 as we like, quietly grazing among the microscopic 

 thickets of fresh-water algae in which they most love 

 to disport. The play of their wheel-like crowns is 

 exceedingly graceful, whilst their bodies are usually 

 so transparent that we can see all the internal move- 

 ments and processes as plainly as if they were con- 

 structed of glass. As its name implies, Rotifer vul- 

 garis is very common, and the student cannot fail 



Fig. 92. 



Rotifer vulgaris. 



to find it in his fresh-water tank. When removed by 

 means of the common dipping-tube, to the slide, and 

 placed under the microscope, it behaves as if it had 

 not been transferred to new quarters, and evidently 

 seems to know that the enormous quantity of force 

 which is given off in its active habits, requires to be 

 replaced by a corresponding quantity of food. Hence 

 the great business of its life seems to be feeding. The 

 rotifer is not a gourmand ; everything seems to be fish 



K 2 



