MEMORANDA. 



63 



box, K K, is a plate, 1 1, supported by two strong curved 

 brackets^ n n, which give great strength and support to the 



plate, 1 1, in which a circular plate is fitted, and to which the 

 top stage-plate, l, is also fixed. By means of the circular 

 plate the upper stage may be rotated. 



This form of stage is exceedingly convenient, and, applied 

 to the more portable instruments, will enable them to work 

 with the same illuminating apparatus as the larger ones. The 

 entire thickness does not exceed one quarter of an inch, and 

 the support brackets are so constructed as to prevent tremor. 



Oscillatoriacese. — When going over some of these organisms, 

 a few days ago, I observed one coiled up like the accompanying- 

 diagram, ni which it will be observed that both extremities of 

 the filament are pointing in the same direction. 



The filament thus coiled continued to revolve steadily upon 



