234 THE MICROSCOPE. [December, 



mother and allowing the young to escape, found them quite able 

 to paddle for themselves. The young measure 5-10 mm., but 

 do not resemble the parent much until about a week old. 



Respiration is carried on by means of branche^e or gills at- 

 tached to the feet, and are made to work quite briskly. 



Circulation is simple, yet complete ; the heart, if so it may be 

 called, measuring about 3-ro mm., is situated in the back of the 

 little creature, a little below the head, and, owing to the trans- 

 parency of the little being, plainly shows its contractions and ex- 

 pansions. The blood is forced forward to the head, slightly 

 downward, around the eye, then along lower side of the alimen- 

 tary canal, then completely around extreme end of the canal, com- 

 ing over the upper surfoce of the canal along the back, and 

 again entering the heart, ready for the next trip. During this 

 journey the gills supply the blood with oxgen extracted from the 

 atmospheric air, contained in the water in this way sustaining 

 the vitality of the blood. 



The alimentary canal is a single tube very nearly straight ; 

 digestion and defection seem best while the animal is in motion, 

 and, by its peculiar motion when swimming, the water (and con- 

 tents) strike its lower surface near the head, in this way creating 

 a constant current directly to the mouth, when it extracts what 

 nourishment it may find from the water as it passes the mouth. 

 Its food seems to be both animal and vegetable matter. 



The eye is round, and, in proportion to the size of the animal, 

 quite large, measuring 2-10 mm., being composed of an inky sub- 

 'Stance, inclined to be gelatinous, undoubtedly taking the place of 

 what, in the human eye, constitutes the vitreous humor and 

 retina, is studded with quite a number of small spherical bodies, 

 measuring 1-20 mm. in diameter, representing perhaps the crys- 

 talline lens ; the whole is inclosed in a sac or membrane, very 

 transparent. The animal has the power of withdrawing and pro- 

 jecting these little spheres, in this black substance, at will. 



These little creatures exist in such vast numbers in some stag- 

 nant pools as to change the color of the water, often giving it 

 a sort of reddish hue ; and on bright days will often form into 

 bands from two to four inches wide, extending many feet into the 

 pond or pool, all moving at the same time, forming a veritable 

 procession, and remaining in line, too. Strange to say, should a 

 shadow fall on part of this band, that portion darkened by this 

 shadow will disappear, but, upon removing the shadow, will re- 

 appear and continue their journey with the remaining portion of 

 the column. 



During my investigations I found that these bits of life were 

 also subject to disease, and, by carefully examining one of these 

 sickly specimens, found it nearly covered with parasites of various 

 shapes, some being rod-shaped, others oval, and a third, a vicious 



