20 THE AMERICAN MONTHLY [Feb 



from its spiral coils. It has a power of movement. The 

 free ends can swing from side to side. This and the 

 previous form often mingle to make artistic rims raised 

 above the hot water pools. They may be seen at Pris- 

 matic Spring in Middle Geyser Basin. In the margins 

 of this spring, 300 feet wide, dark-blue at center, are 

 beautiful shades of green to light yellow. Over the rim 

 splashes the hot water. The wet algae are too hot for 

 one to hold them and one need not venture too near it. 



Anabcena. — In the cooler places we begin to discover 

 diatoms and a specie of Anaboeaa, one of the family of 

 Chlorophycese. 



GrLCEOCAPSA. — This is a unicellular alga, figure 9, having 

 very thick cell walls made up of an outer gelatinous 

 layer and others concentric in arrangement. These slimy 

 filaments are constantly damp from the condensation of 

 steam that arises and meets them. The students of algae 

 find rich harvests of Schizophytes and Cyanophytes at 

 these hot springs. 



Some Photo-Micrography Experiments. 



By a. WOOLSEY BLACKLOCK, M. D. 



T use a hand-camera for this purpose. Fair results 

 can be got by adjusting the lens to its solar focus or for 

 distant objects. Recent experiments as follows have im- 

 proved the results: 



I focussed an object carefully with the eye in the 

 usual way, placed a camera with its objective close to the 

 eye-lens of the microscope, and shifted the ground-glass 

 until I secured a thoroughly sharp image of the object 

 on it. I then removed the camera, without changing the 

 relative positions of the objective and ground-glass, and 

 having made a few fine scratches through the film of a 

 spoiled negative, I placed this in front of the objective of 

 the camera, and moved it about until the scratches were 



