846 
Proceedings of the Boyal Society 
Cladophora cegagropila of Rabenhorst, described and pictured in 
Hassall’s Algce, p. 213, in part. IJiave had two diagrams prepared 
showing (a) the appearance of the alga under the microscope, and 
(b) a highly-magnified view of one of the filaments ; and I am able, 
by the kindness of Professor Dickson, to show under the microscopes 
in the ante-room portions of the coverings of these balls (see 
Plate XXX., figs. 4, 5, and 6). I must express my special thanks to 
Dr J. M. Macfarlane, to whom I am indebted for the microscopical 
preparations, and for much kind assistance in other ways. Under 
one of the microscopes will be found a slide showing a portion of 
the contents of one of the balls. The interior is seen to be filled 
with diatoms and the decomposed remains of the inner ends of the 
radiating filaments. Some of the filaments exhibit fructification, 
the cell contents in several of them being differentiated into spores 
which in time will be set free to propagate the plant. 
The loch in which these balls are found — Lower Kildonan by 
name — is an irregular sheet of water, less than half a mile across in 
any direction. It lies near the west coast of the island, and is con- 
nected with the sea by the so-called “river” Roglass, which is, in 
reality, little more than a large ditch some 8 feet broad and about 
three-quarters of a mile in length. The whole of the west side of 
South Uist is very flat, and the loch itself lies only a few feet above 
the sea-level. Lower Kildonan is a fresh- water loch, being connected 
with several other inland lochs, as will be seen from the Ordnance 
Survey map ; and its water, except when and where the tide from 
the Roglass enters it, is fresh. It is, however, precisely at this part 
of the loch where the water is occasionally rendered brackish by 
the tide that these balls occur, and this is interesting in view of the 
fact that Cladopliora cegagropila is found both in fresh and salt 
water. The loch here is quite shallow, and the bottom seems to be 
a mixture of sand and mud, the former predominating. The balls 
lie in a depth of 2 to 3 feet, and cover areas of many square yards, 
showing conspicuously by their dark colour against the light sandy 
bottom. They lie alongside of one another in great numbers, and 
vary in size from about a quarter of an inch to 3 or 4 inches in 
diameter. In some cases a complete small ball is found inside a 
larger one, and a specimen of this kind is on the table. Mr Mac- 
Lean of Milton told me he had frequently seen balls containing 
