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EDITORIAL GLEANINGS. 



At a recent meeting of the Zoological Society of London, Dr. S. E. 

 Harmer, F.R.S., E.Z.S., read a paper on " The Polyzoa of Water- 

 works." He gave some account of the serious trouble which had been 

 caused by the occurrence of a rich and varied fauna in the pipes of 

 certain foreign waterworks, notably at Hamburg and Eotterdam. As 

 was first shown by Kraepelin, the Polyzoa play a prominent part in 

 the activity of the pipe-fauna, by feeding on Diatoms and other 

 microscopic organisms, and serving in their turn as the food of other 

 animals which prey on one another. The nutritive matter rendered 

 available by the presence of enormous numbers of Polyzoa is thus 

 in large measure responsible for the existence of other constituents 

 of the fauna, which may include even fishes, such as the Eel and 

 the Stickleback. The organic material supplied by the disintegration 

 of the Polyzoa and other animals is believed to be important for the 

 nutrition of Iron-Bacteria, which are well known to cause the most 

 serious trouble in waterworks. 



He then gave some account of five cases, which had recently 

 come under his own observation, of the occurrence of Polyzoa in 

 English waterworks in sufficient numbers to give rise to very' serious 

 inconvenience. In one or two of these cases the advice given by 

 Kraepelin, in his paper on the Hamburg pipe-fauna, was being 

 followed, by the introduction of a system of filtration, the principal 

 object of which is to remove the microscopic organisms on which the 

 Polyzoa, and ultimately the whole assemblage of animals in the 

 pipes, depend for their nutriment. 



The Polyzoa found in the five systems considered were referred 

 to four species, and some account was given of the synonymy and 

 distinguishing features of these. One of the species found was 

 Paluclicella articulata, Ehrb., and the specimens were remarkable 

 for the profusion with which hibernacula or winter-buds were being 

 produced. The examination of the hibernacula resulted in the dis- 

 covery of some evidence with regard to the mode of development of 

 these structures — a subject on which no observations appear to have 

 been hitherto published. The evidence recorded may have some 



