256 THE POPULAR SCIENCE MONTHLY. 



the picture, but p h is the throat, and this is followed by the sac- 

 like " stomach-intestine," d. These worms propagate likewise by- 

 simple fission, after a new brain-ganglion has been formed at th s t, 

 by the thickening of the two sides. A new mouth is formed by a 

 drawing in of the outer skin. On either side of the head there 

 is a little indentation in which longer hairs are growing. These 

 are probably organs of sense; however, their function has not 

 yet been determined. 



Figs. 7 and 8 show a pair of crab-like animals, which are 

 among the regular inhabitants of wells. Fig. 7 is a cyclops ; Fig. 

 8 represents a crustacean, the Cypris. The latter is rather a 

 peculiar object, as the animal is inclosed in a shell-like structure, 

 called a carapace, from which only a pair of caudal appendages 



____ protrude, which are provid- 



^^r^^w^^s^ ^ ^apg^— ^- e d with bristles and serve 



<Sgfi0^^ < ^H^S^^^^?' : * for the purpose of locomo- 



^^mMi' ^mmw~ ctf ^* ^ on > oc * s ^ e G ^ e ' 



^^^fe^&^.:„^ • y ; ^-%^H^^- -^ considerable number 



--Ml . Jls^ =r ~~~' of species of cyclops are 



//WffjFiu '" JV\> to be found in the mud 



/ J ] 1 of wells. Fig. 7 shows the 



FlQ 8 Cyclops nanus. This lit- 



tle animal travels rapidly 

 through the water by means of its swimming apparatus, to which 

 the powerful muscles (m) lend considerable assistance. The 

 female carries two ovisacs (ei) with numerous eggs ; oc, at the 

 front part of the body, is the eye, which is of a reddish or brown 

 color and possesses a fine lens. 



In this article we have enumerated and pictured only the prin- 

 cipal representatives of this fauna of the wells, so that a general 

 idea might be gained of the appearance of the animals which live 

 in the turbid water of wells. However, to show how rich in 

 numbers this little animal world is, the fact should be mentioned 

 that Prof. Vejdovsky, after his careful examination of the water of 

 two hundred and thirty-one wells of Prague, was able to announce 

 the existence of — (1) twenty varieties of amceba-like organisms ; 

 (2) twelve varieties of flagellate infusoria ; (3) forty-five varieties 

 of other infusoria ; (4) twenty-four varieties of worms ; (5) ten 

 varieties of Crustacea — making altogether a total of one hundred 

 and eleven species of organisms. Most of these varieties were 

 found in wells which had been polluted by the infiltration of 

 urine and decaying organic matter. The organisms carried down 

 by the surface water into these lower regions had found abun- 

 dant food there, and were thus enabled to continue their exist- 

 ence. With regard to the question as to whether the water from 

 wells that show an abundance of these forms of life is dangerous 



