ROTATORIA. 169 



family of 1,000,000, in eleven days 4,000,000 ; and in twelve days tlie 

 venerable progenitor was surrounded by 16,000,000 of an active, 

 happy, energetic race, ceaseless in search of prey, and a famous feast 

 for a larger animal. 



The Rotatoria delight in the sunshine ; and when the bright lumi- 

 nary is hidden behind clouds, the animals sink down to the bottom of 

 the water, and there remain. When the water of their haunts is be- 

 coming much evaporated, they rise to the top, and give a bright-red 

 tint to it ; but when caught and placed in a jar, their beautiful colour 

 fades in a few days. Locomotion is performed by swimming, the ro- 

 tatory action of the crowns of cilia impelling it forward ; in other 

 instances it bends its body, then moves its tail up towards the head, 

 which it can do from having two processes that serve as feet near to 

 the tail ; it then jerks its head to a further distance, again draws up its 

 tail, and so proceeds on its journey. Another peculiarity they possess 

 of drawing in the head and tail until nearly globular, from remaining 

 in this condition fixed by the sucker ; at other times they become 

 a complete ball, and can be rolled about by any agitation in the water. 



The eggs are of an oval form, and from twenty to thirty may be 

 seen in an animal. Some are of a brown colour, and others of a deli- 

 cate pink and deep golden yellow. In those of a light colour, the 

 young may be seen with their cilia in active vibration. 



The body of the wheel-animalcule is of a whitish colour ; its form 

 will be seen by the engraving ; and its tail has six points. The tube 

 for respiration appears to allow of water passing to the inside. On the 

 food being drawn by the currents to the cup part of the wheels, it 

 passes down canals in the neck to the mouth, which is situated at the 

 lower extremity of that part of the body. The food is crushed by the 

 teeth on the plates of the jaw, with an action like a hammer. From 

 this it passes on to the alimentary canal for the sustenance of the 

 animal. 



BRACHIONiEA. 



Ehrenberg's genus BracMonus, or Spine-hea/ring Animalcule, be- 

 longing to the Rotatoria, are truly interesting from their perfect, high, 

 and complex organisation. Some are entirely enclosed in a shell, and 

 others only partially covered. Their structure is so beautiful and sym- 

 metrical as to cause them to be favourites with those who delight 

 in the studies of microscopic observation. 



BracMonus SPriatus, or Sta-iped Shell Ammalcule (No. 3, fig. 101), is 

 of an elegant, jug-like form, the transparent shell being flluted length- 



