biological study of tap water. 425 



Metazoa. 



The other animal forms which have been noticed are not very 

 numerous. 



Vermes. — The worms are represented by the Nematoid Anguillula 

 fluviatilis, which is not very common ■ and by one or two species of 

 Rotifera belonging to the family Brachionidae, in which there is a 

 carapace and one or more eye-spots. These are Anuraea stipitata, 

 and another species with the back of the carapace ornamented with 

 facets, as well as furnished with teeth in front. A species of the 

 genus Brachionus itself has also been observed. 



Arthropoda. — The Crustacea are represented by at least two 

 species, Cyclops quadricomus and Daphnia pulex, or a nearly allied 

 form. Cyclops especially is common both in the adult and larval 

 stages. 



Belonging to the Tardigrada I have noticed a species of Macrobi- 

 otus rarely present, probably M. Hufelandii. 



Epithelial cells, bristles of Crustacea and insects and other frag- 

 ments are to be found among the debris which is always present in 

 considerable quantity, and which is generally described as " flocculent 

 matter." It consists mainly of broken Diatom frustules, as a good 

 deal of it remains after boiling in nitric acid, partly also of decom- 

 posed organic matter in a fine state of division, as well as a small 

 quantity of mineral matter. 



The bearing which the foregoing observations have on the question 

 of the purity of Toronto's water supply may now be briefly alluded 

 to. Judging from the miscroscopical examination of the suspended 

 matter in the water, I would charactei'ize it as one of the purest 

 of natural waters, inasmuch as it is almost entirely free from any 

 organisms which are either themselves directly injurious, or which, 

 by their presence, would show that water containing them must 

 necessarily be injurious. The great bulk of the sediment consists of 

 vegetable matter, and that in a living condition. The animal forms 

 are chiefly Flagellate Infusoria, which are inhabitants of fresh water, 

 not depending for their food on dead, decaying, and poisonous 

 matter. 



The absolute amount of sediment in the water I cannot accurately 

 state ; but the chemical analyses show the amount of albuminoid 

 ammonia to be very small (averaging - 003 — '007 grains per gal.) ; 

 30 



