436 DR. S. F. HARMER ON THE 



C. Chajjman, M.In!^t.C.E., Water Engineer to the Borough of 

 Torquay. I am greatly indebted to Mr. Chapman for the 

 trouble he has taken in giving me the fullest information with 

 regard to this particular occurrencej and in calling my attention 

 to similar instances in other places. 



The Torquay case is one of the usual kind, in which no efficient 

 system of filtration had been in opei'ation. In spite of this fact 

 no trouble had been given by the growth of Polyzoa or other 

 organisms, in sufficient quantity to give lise to anxiety, during 

 fifty years. The apparently sudden invasion may perhaps have 

 been due to the fact that the Polyzoa in question had not 

 previously effected an entrance into the system. The Plumatella 

 was first observed in pipes which had been in use a little moie 

 than two years. The pipes were at the bottom of a steep hill, on 

 a trunk-main which supplied a large part of Newton Abbot, and 

 where the fl.ow of water was constant and of considerable velocity. 

 The Polyzoon was soon traced in every direction all over the 

 system, both at. Torquay and at Newton Abbot. It quickly 

 began to give rise to serious inconvenience, by becoming detached 

 from the walls of the pipes and by being carried to the ball-taps 

 and the strainers of meters, which became blocked and were thus 

 thrown out of work. The trouble became specially acute imme- 

 diately after a frost in the early part of 1912. This is entirely 

 in accordance with expectation ; the Plumatella which had been 

 growing on the walls of the pipes having no doubt broken up 

 during the cold weather, its branches having then passed into the 

 flow of water and so having given rise to the choked taps and 

 meters which were reported in large numbers. In one case men- 

 tioned to me by Mr. Chapman, eleven houses in one block of 

 buildings were without water owing to this cause. It need 

 hardly be remarked that the well-known habit of dying a,t the 

 end of the year gives these freshwater Polyzoa special advantages 

 in distributing themselves over a wide area of a system. It is 

 only necessary for statoblasts or fragments of branches containing 

 them to remain attached to some irregularity on the inside of a 

 pipe to make it practically certain that some of them will have 

 the opportunity of germinating in the next period of warm 

 weather. 



No complete examination of the pipe-fauna has been made in 

 the Torquay Waterworks, but a few other animals have been 

 observed in them. One of the most conspicuous of these is a 

 Freshwater Sponge, which has been found growing on the insides 

 of some of the pipes, and has been detei-mined by Mr. R. Kirk- 

 patrick as Ephydatia fluviatilis. In some of the samples there 

 were large quantities of a Dipterous larva, of a bright red colour. 

 These have been determined by Mr. F. W. Edwards as a species 

 of Chironomus. The majority of these larv«, and perhaps nearly 

 all of them, could hardly have succeeded in completing their 

 metamorphosis ; and it seems probable that, as in the case of the 

 Dipterous larva; recorded by Kraepelin (85, p. 11), the trans- 



