" BREAKING OF THE MERES." 117 



exactly of that colour. The ducks had left the pond altogether, 

 and certainly no carman would have thought for a moment of 

 watering his horses there. On the bank the substance was 

 collected in masses ; the small waves caused by the wind had 

 driven it on shore, and it would have been easy to gather 

 it up with a shovel. When we consider what the organism is, 

 and its minute size, it seems marvellous that such an amount 

 <.'Ould have originated in such a small area of water. From 

 this time the organism gradually lessened ; and on a visit about 

 a month after, the pond had regained its normal condition and 

 appearance, and though I diligently searched for half an hour 

 I could not procure a single specimen. 



The organism proved to l)e one of the Oscillatoriae. These 

 are very common and minute plants belonging to the lowest 

 class, the Blue-green Algae or Myxophyceae. I did not find 

 it possible to identify the species, nor could any one to 

 whom it was shown. West mentions the two species named 

 in the report, and Dr. Cooke has one he calls Lyngbya 

 ochracea, but the details given are in neither case sufficient 

 to justify a definite statement. The plant consists of fila- 

 ments formed of a single row of cells about 3'5/x broad, 

 and usually nearly the same in length. These cells are filled 

 with protoplasm of a yellow-ochre colour during life, and in 

 each there are several highly refractive bodies of various shapes ; 

 sometimes these nearly fill the cell, and there is reason to believe 

 that they consist to a considerable extent of sulphur. The 

 filaments readily break up, but when grown without disturb- 

 ance probably reach a considerable length. They have the 

 usual characteristic movement of the Oscillatoriae. When 

 floating free they bend from side to side and move forward 

 slowly in the direction of their length. The most noticeable 

 feature is the colour, to which I will refer presently. [A sketch 

 of the organism was exhibited, but the highly refractive bodies 

 spoken of are most difficult to represent adequately ; they change 



