ALG.E 133 



" But who hath praise enough? nay, who hath any? 

 None can express thy works, but he that knows them ; 

 And none can know thy works, which are so many, 

 And so complete, but only he who owes them. 

 All things that are, though they have several ways, 

 Yet in their being join with one advice 

 To honour thee ! and so I give thee praise." 



Green Lake. 



The name of Glas-lough, or " green lake," has been 

 applied, from time immemorial, to a lake in the 

 county of Monaghan, in Ireland, on account of the 

 hue of its waters, the cause of which was investigated 

 by Dr. Drummond in 1837, with the result that it was 

 caused by the presence of minute vegetation. He 

 says that " when a little of the water is lifted in the 

 hand it seems perfectly transparent, and it appears 

 equally clear at the edges of the lake, in a depth of 

 not more than a few inches, and there the pebbles at 

 the bottom show perfectly distinct, without any in- 

 termediate cloud to obscure them. But at a depth of 

 two feet the bottom is undistinguishable, and the 

 water presents a sort of feculent opacity, accompanied 

 with a dull, dirty, greenish hue. On lifting some of 

 this in a glass it seems at first sight quite transparent, 

 but, on holding it up to the light, innumerable minute 

 flocculi are seen floating through every part of it, 

 and producing a mottled cloudiness throughout the 

 whole." 1 



The microscope revealed that the minute flocculi, 

 in suspension, were the very fine filaments of a species 

 of fresh-water alga, belonging to the genus Oscillaria, 



' " On a New Oscillatoria," J. L. Drummond, M.D., in A n/ia/t 

 of Natural History, March, 1838. 



