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Note on a Salt-Water Monad. 



By E. M. Nelson. 



(Read June 25th, 1886.J 



Last year I placed some jelly-fish in a 12oz. bottle of fresh sea- 

 water. In about a week all the jelly-fish were dead with the exception 

 of one, which kept alive for three or four months . The bottle was not 

 touched, and on examination this year I found a brownish growth 

 on the sides and bottom of the bottle, and a slight growth of a green 

 alga. Microscopical examination revealed the presence of an 

 enormous quantity of amaabaj, and small uni-flagellate monads. 

 The monads swam rapidly with a wavy, rotary motion. After a 

 little while the motion became jerky, a monad bounding forward 

 short distances, frequently stopping for an instant to change its 

 direction. The distance of its forward movement gradually 

 shortened, till at length it did not leave the field of a high power 

 (1,000 diam.). During all this time the flagellum could be easily 

 seen. The linear motion now became changed to a rotary motion, 

 the flagellum was much shortened and was difficult to observe. 

 The organism, moreover, gradually assumed a spherical form. When 

 the rotary motion had well set in it was very rapid, and nothing 

 more could be seen of the flagellum. During the rotary motion the 

 organism did not travel about, but kept to one place. The rotary 

 motion gradually slowed down until it stopped. The monad was a 

 reddish-brown colour and contained a spot like a cell nucleus, rod- 

 shaped bodies like bacteria, and minute dots like micrococci. A 

 moment after the rotary motion of the monad had stopped a move- 

 ment among a few of the micrococcal forms began. This movement 

 was soon communicated to the rest, and also to the rod-shaped 

 bodies. The organism gradually lost its colour and consistence, 

 soon becoming nothing more than a transparent globe filled with 

 moving bacteria. In some instances it burst, when a portion of the 

 bacteria escaped and swam off. On one occasion, when one burst, I 

 saw the flagellum — which appeared to be of full length — thrown 



