268 MICROSCOPY FOR BEGINNERS. 



mouth is a small opening at the front of the part repre- 

 senting the head. It is followed internally by two short, 

 somewhat curved and diverging rods, said to be used to 

 wound the prey. The so-called gizzard, at a short dis- 

 tance from the mouth, is plainly visible through the 

 transparent body. It has no motion. Two small eyes 

 are usually present, one on each side of the head. The 

 animal's movements are very slow and awk- 

 ward, the creature appearing to work hard, 

 with but little result so far as progress is 

 concerned. 



Macrobiotus is produced by eggs, which 

 water-bear are deposited in an interesting way. When 



(Mncrobi6tus). 



they are suinciently matured, the water-bear 

 sheds its skin and leaves the eggs in the empty and cast- 

 off case. It is no unusual occurrence to find the empty 

 skin of Macrobiotus with the empty eggs inside, the 

 young having escaped. The young resemble the par- 

 ent, it is said, in all except size. 



This strange, bear-like creature is to be found quite 

 often at the bottom of shallow ponds ; or, if an aquari- 

 um is kept, it will be almost sure to make the bottom 

 its home. It is entirely invisible to the naked eye, meas- 

 uring rather less than one-sixtieth of an inch in length. 

 On account of their slow movements, the water-bears 

 are often called Tardigrades. The scientific name of 

 the common American form is Macrobiotus Ameri- 

 ctinus. 



