1 I.-, 



While examining specimens in the living state recently, an 

 organism known as a Rotifer, a member of the animal kingdom, was seen 

 actually engaged in devouring cells of the Cosmarium. A- these small 

 animals are practically i ransparenl . the process of digestion can be seen 

 ffoino 1 on inside the body of the animal, and the Cosmarium 

 after being swallowed was easily distinguished. 



Soi ue of 01 1 r friends may say ; but if water contains animal organisms, 

 it cannot be lit for consumption. That of course, is bu1 a natural 

 conclusion: bul it' they were asked to condemn water because a 

 small fish was seen to be swimming in it. they would besitate to do so. 

 Yet the fish would probably be the agency for contamination, a 

 million times greater than would the Rotifer. 



Fish must be admitted to contaminate water, but at the same 

 time the degree of purification they perform by feeding upon more 

 objectionable organisms, more than negatives the amount of contamina- 

 tion they actually occasion. Now. the fish eats the Rotifer, the rotifer 

 eats the Algae, and by this means the balance of nature is preserved, 

 and it is only when such balance is upset by one or any of the chain of 

 organisms engaged, that humanity suffers by the water becoming 

 •contaminated to a pernicious degree. 



It, is certain that neither the fish, the rotifer or tin- Algae can 

 exist in largely contaminated water, and while the balance of nature 

 is fairly preserved and none of the agents at work, are present in 

 excessive numbers, their harmless character should not be doubted. 



It is patent, however, on the other hand that Alga; can really 

 become the primary means of water contamination: and evidence of 

 this is afforded by recent observations. A quantity of the given 

 matter from the sides and bottom of a reservoir was secured. The 

 latter was found to be chiefly composed of various species of Diatoms, 

 while the sides afforded specimens of a filmentous Alga; known as 

 Spyrogyra, as well as a few species of the Diatomacea; comparing with 

 those found on the bottom. When these samples were first brought 

 in thi' water was lested, and found to be practically free from ammo- 

 niacal contamination, but making a home among the Alga; were found 

 numerous forms of micro-animals, which were soon killed by the 

 weight of the accumulated material, and when the water was tested 

 twenty-four hours afterwards, it was found to be largely contaminated. 

 Therefore, although the Alga; was the primary means, still in reality 

 it was the dead members of the animal kingdom which in this case 

 caused the real contamination and it was the scraping out and placing 

 together in masses, which caused the contamination. In clearing a 

 reservoir, however, such a mass is not allowed to remain in contact 

 with water. 



Again it is known that some few species of Alga; do communicate 

 to water certain objectionable tastes ; and it is quite clear also that 

 Alga; in a decayed state will become as great a source of contamina- 

 tion, as would indeed any other kind of vegetable matter in a state ot 

 decay : but in themselves, and when in a healthy growing state, and 

 in moderate numbers, they are certainly not to be feared. Those that 

 cause objectionable tastes should certainly be at once removed, but it 

 is seldom that such species appear, the harmless kinds being much 

 more in evidence. 



It has moreover been found that the presence of a layer of eame 



