BULLETIN OF THE BUSSEY INSTITUTION. TT 
the sea-shore as well as in fresh water, but are particularly common in 
hot springs. Cohn has shown that the peculiar exhalations of hot 
sulphur springs are owing to the growth of species of Beggiatoa,* 
which depend for their existence upon, at least, two conditions ; the 
presence of a large amount of sulphur in the water, and the absence 
of iron. Cohn confirms the observations of Cramer, that the dark 
granules in species of Leggiatoa consist of sulphur. When Leggiaioa 
filaments are heated, the granules fuse into large yellowish drops and 
a sulphurous odor is developed. If the filaments are treated with 
sulphide of carbon, the granules are dissolved, and then the cell parti- 
tions become for the first time visible. 
The odor produced by decaying alge of the order Wostochinee was 
brought most strikingly to our notice during the last summer. In the 
month of August, we were asked to examine the waters of Horn 
Pond, situated in the town of Woburn, nine or ten miles from Boston, 
and the head-waters of what is known as the Mystic basin, which 
supplies Charlestown and Kast Boston. It was stated that a disgust- 
ing odor, said to resemble that of a pig-pen, had appeared in several 
portions of the pond. On inquiry, we found that there had been a 
quantity of a plant called eel-grass washed ashore, and upon it was a 
slimy mass from which the odor seemed to proceed. ‘The slimy masses 
were not limited to any particular part of the pond, and, although very 
abundant at the upper end, they were also common at the outlet. At 
the time of our visit they were said to be by no means as numerous 
as two or three days before. The eel-grass, so called, to our great 
surprise, proved to be not what is generally known by that name 
(Vallisneria spiralis) or even any of the common pond-weeds (Pota- 
mogeton, Myriophyllum, Ceratophylium), but a new species of Plec- 
tonema,t of the order Nostochinee, which we had never seen growing 
* For an account of the physiological and chemical relations of the genus 
Beggiatoa, vid. “ Beitrige zur Biologie der Pflanzen,” by Cohn, Vol. 1, Part IIL, 
pp. 172-180, where references are given to the earlier writings of Cohn and others 
on this subject. 
+ Plectonema Wollei,n. sp. Trichomatibus atro-viridibus in massas_pluri- 
pedales intricate coalitis ; ramis parcibus obtuse exeuntibus plerumque singulis 
rarissime geminatis. ‘Trichom. diam. .00388 m. m.; c. vagina .00405 ; articulis 
circa .000485 m. m. latitudine. Species magnitudine et ramis parcibus facile 
distincta. Species generis nobilissima a cel. Wolle prope Bethlehem in Pennsyl- 
vania primum inventa est. Ad Horn Pond prope Boston detexi. Species a cel. 
Rabenhorst in Algis Europeis, no. 2440, sub nomine Lyngbya Wollei, Farlow, 
distributa est. 
