FRESII-WATER A L G .E OF THE UNITED STATES. 17 



of course, soluble in ether and alcohol but not in water ; but the Phycocyan (Cohn) 

 is insoluble iu alcohol and ether, but soluble in water after the death of the oscil- 

 latoria. It is precipitated out of its solution by acids, alcohol, and metallic salts, 

 as a blue jelly, but potash and ammonia tiirow it down as in a colorless, gelatinous 

 mass. I have myself frequently noticed that oscillatoria after death will yield a 

 bluish coloring matter to water, but thought that such coloring matter was the 

 result of a partial decomposition, and I think that Professor Cohn has by no means 

 established as a fact that his Phycocyan exists in the oscillatoria during life. 



As to the method of reproduction of these plants, we are as yet almost entirely 

 in. the dark. Individuals do multiply by the breaking up of the internal endo- 

 chrome into masses or sections through a separation at the joints. These little 

 masses frequently grow immediately into new individuals. Sometimes, however, 

 they roll themselves into a ball, but whether they then have the power of coating 

 themselves with a protective wall and passing into a sort of resting spore or not, I 

 cannot say. 



The specific characters of the oscillatoria arc derived from the color, form, mode, 

 and place of growth, &c., of the large common mass, its thickness, consistency, 

 the absence or presence of radii, &c. Descending to the individual filament, the 

 characters are drawn from the size, the color, the length of the articulations, and 

 the shape of the uninjured ends. Thus, it is to be noted, whether tlie latter arc 

 gradually narrowed (attenuated), or preserve their size to the very point, whether 

 they are acutish or obtuse, rounded or truncate, whether they are straight or con- 

 stantly curled. The activity and modes of motion are also to be remarked. Some 

 species merely glide across the field of the microscope, some are constantly curling 

 and uncurling at their ends, some bending to and fro almost like a pendulum, some 

 are very sluggish, others very active and restless. 



After all, however, it must be confessed that the specific characters are very un- 

 satisfactory, much more so than in any other phycochroms which I have studied. 



A very large number of European forms have been described, some few of which 

 I have been able to recognize. I have also ventured to name a few forms appa- 

 rently distinct, but have refrained from going farther into their specific study, 

 because I have found it so unenticing, and my time has been so limited. 



Professor Bailey, in Silliman's Journal, N. S., vol. iii., states that he has identified 

 a few species of this family, although with great hesitation and doubt. At the 

 time he wrote there were really no known grounds upon which specific unity could 

 be predicated in these plants, and I therefore think that his identifications arc of 

 but little value, although holding the most profound respect for his abilities as a 

 naturalist. The list he gives is as follows : — 



0. tenuissima, Ag. Warm Springs of Washita. 



O. (enuis, Ag. Providence, Rhode Island. West Point, New York. Culpepper 

 County, Virginia. 



O. decordcans, Gener. Common everywhere on pumps, &c. 



O. muscorum, Ag. West Point, New York. 



O. nigra, Vauch. West Point, New York. 



0. corium, Ag. 



3 February, 1872. 



