36 THOUGHTS ON ANIMALCULES. 



YIII. 



THE MONADS. 

 Plate II. 



In tlie group under tlie microscope, some minute 

 points, or globules, of various colours, may be observed 

 gliding rapidly along in various directions: these are 

 called Monads. A few have been transferred to a drop 

 of water, and, to distinguish their true characters, we 

 must view them with glasses that magnify from 300 

 to 400 times in linear dimensions. We may now per- 

 ceive {see pi. II, figs. 3, 7), that each individual is an oval 

 or spherical transparent cell, containing granules, or 

 little specks, of some coloured matter. Some are with- 

 out eyes, or any sensible organs but the cilia, and one or 

 more filiform spines or bristles, (pi. ii, figs. 4, 5, 8); 

 others have a red eye-speck, (ocellus); and many have in- 

 durated cases or shells. They vary in size from one two- 

 thousandth to one three-thousandth of a line in diameter: 

 a drop of water may, therefore, contain 500,000,000. 

 Some are of a bright green colour, {Monas grandis)\ 

 others pink, red, yellow, bluish, ochreous, (pi. ii, figs. 



