Proceedings. 17 



habitat for these plants. They occur in these situations in 

 great variety. The water is stationary as well as flowing 

 at varying rates of speed, deep and shallow. Variations 

 occur mainly in the forms of the leaves, and are probably 

 due to the local condition of the water in which the plants 

 grow. Thus the same species will have broad leaves in one 

 situation, and leaves of an entirely different form in another 

 situation. On a much smaller scale, similar conditions 

 occur in the meres and streams of Cheshire, and among the 

 fens of the eastern counties of this country. Special atten- 

 tion was drawn to the series of Potamogeton gramineus, 

 Linn. ( = P. heterophyllus of British botanists), and to 

 P. nitens, Web., one of the Scotch pond-weeds. The 

 specimens were beautifully preserved, and the whole series 

 is likely to prove of great value to students of the genus, as 

 they are accompanied by critical notes upon the new forms 

 which Dr. Tiselius has differentiated. 



\_Microscopical and Natural History Section.'] 



Ordinary Meeting, December 17th, 1894. 



JOHN Boyd, Esq., President of the Section, in the Chair. 



Mr. BROADBENT described further observations made 

 by him on the Infusoria. 



Mr. BOYD drew attention to a plague of fleas that had 

 infected a refuse heap, on which a cucumber frame was 

 placed, in a garden at Bowdon, after a long spell of fine 

 dry weather this summer. Fleas are known to lay their eggs 

 and to pass their larval and pupal stages in the bed of their 

 host, and from the rapidity with which they breed under 

 favourable conditions it would appear that for some 

 generations at least they can dispense with a host ; as, on 



