ii4 
BREAKING OF THE MERES. 
memorial on account of the hue of its waters, which exhibit a 
green tinge, equal to, or exceeding in intensity, that of the sea, 
though it is not at all times equally striking. “ From the accounts 
I received, the green colour is evident in the lough throughout the 
year, and if I may judge from my own observations, every drop 
of it is impregnated with the oscillatory filaments.” “ When a 
little of the water is lifted in the hand it seems perfectly trans- 
parent, and it appears equally clear at the edges of the lake, but 
at a depth of two feet the bottom is indistinguishable, and the water 
presents a sort of feculent opacity, accompanied by a dull, dirty, 
greenish hue. On lifting some of this in a glass it seems at first 
sight quite transparent, but on holding it up to the light innu- 
merable minute flocculi are seen floating through every part of it, 
and producing a mottled cloudiness throughout the whole.” At 
first I could only find the plant diffused through the water, but at 
length I discovered a wet ditch extending from the lake into an 
adjoining field, and there it appeared swimming on the surface in 
large masses several inches in thickness and above a foot and a 
half in length. These seemed evidently to be produced by an 
agglomeration of the filaments floated in from the lake, matted 
together at the surface, and increased in growth. The surface of 
these masses, where dried by the contact of the air, was of a 
bright bluish verdigris hue, while the parts immersed in the water 
were of a dull opaque green.” 
On examining specimens in the microscope I sometimes 
observed their motions to be very vivid, and in other instances 
little or no motion could be perceived. They are extremely minute, 
their transverse strife very numerous, and at distances of about 
half a diameter from each other. The filaments in the conglo- 
merated masses appeared to me to be many inches long, and 
running parallel together; the broken fragments dispersed through 
the lake cross each other in all directions.” 
For this species the name of Oscillatoria cerugescens was proposed, 
and under this it is recorded in Harvey’s “ Manual” (p. 163). 
In the same memoir as the above a summary is given of the 
facts narrated by Decandolle of the occurrence of .Oscillatoria 
rubescens in Lake Morat, in Switzerland, which is related to the 
present subject. It is stated that Lake Morat during every spring 
presents the appearance of a reddish scum on the surface, which 
the fishermen express by saying that the “ lake is in flower.” In 
the spring of 1825 this phenomenon was so remarkable as to strike 
with astonishment the inhabitants of its banks. In this year the 
red appearance continued from the month of November till May, 
and its unusual exuberance was supposed to originate from the 
great mildness of the winter, and the consequent smaller elevation 
of the water of the lake being favourable to the development of the 
matter, which was evidently organic, and caused the redness. 
During the early hours of the day the lake presented nothing 
remarkable, but soon after there appeared long, red, very regular 
and parallel lines along its borders and at some distance from the 
shore. The breezes urged this matter into the little creeks, and 
