MEMORANDA. 171 



lating system, and obtain a thin serous fluid lor their nourish- 

 ment, they then become so far developed that they may be 

 readily diagnosed in the animal structures as corpuscles of 

 starch. — S. J. Stratford, M.R.C.S., England ; Editor of the 

 ' Upper Canada Medical Journal,' Toronto, Canada West. 



Structure of cioMterium. — A paper in the last number of the 

 * Microscopical Journal,' by the Hon. and Rev. S. G. Osborne, 

 on tlie Economy of Closterium Lunula^ induces me to offer a 

 few remarks on the same topic, as, though my observations 

 have been trifling compared with the labour which Mr. Osborne 

 has devoted to those beautifully interesting objects, some draw- 

 ings and jottings in my note-book entirely coincide with his 

 illustrations, and afford one or two additional details. 



In February 1853, I first noticed around the margin of a 

 C Lunula the appearance of a double circulation passing in 

 opposite directions through canals or vessels, one of which 

 was, probably from refracticm, of a bright pink colour, the 

 other a pale green. The motion of the currents was nearly 

 uniform, but occasionally intermittent ; and sometimes for a 

 few moments the direction of the currents would appear to be 

 reversed. The circulating liquid carried with it minute 

 granules by which its course and velocity were apparent ; and 

 on carefully observing these, it was evident that the marginal 

 vessels poured their ctmtents into a diffused cavity, free from 

 endochrome, surrounding the hyaline vesicle with its per- 

 plexingly active group of moving bodies. These vary in number 

 from sixteen to twenty or tliirty at each extremity of the frond ; 

 and a supplementary vesicle is sometimes added, containing a 

 single granule in equally brisk activity. The transparent 

 membrane of this terminal cavity of the frond appears covered 

 with cilia, which I have also distinctly seen fringing the inner 

 margin of the crescent, and less clearly also on its outer edge. 



The appearance of a marginal circulation, which passes 

 uninterruptedly across the central band of the Closterium, may 

 or may not be due to ciliary motion, or currents thereby in- 

 duced. But besides this (apparent) circulation in marginal 

 vessels, there is a frequent irregular movement of granules of 

 endochrome more resembling imperfect cyclosis ; and a de- 

 tached granule is occasionally seen to stray into the marginal 

 current, and to be carried by it to the terminal cavity, where it 

 appears to have lost its way and to seek in vain for a resting 

 place. 



Another point to which I would ask attention is the occur- 

 rence of remarkable circular marks or apertures, which are 

 observed more or less distinctly on many specimens of Clos- 



