13 
previous temperature, they revived and came again to the surface. 
From experiments he had made at Herne Bay, he believed that 
there was only one species of Ostrea. He had obtained some of 
the large coarse-shelled Welsh oysters, and, on putting them into 
the experimental oyster beds, he found that in course of time they 
formed new growth of shell, identical with that of the true native. 
He had also placed American oysters in the same beds, .but the 
growth of the shells had not been sufficiently marked to be con- 
clusive. 
A cordial vote of thanks was passed to Mr. Johnson for his 
interesting lecture. 
_ April 19th, 1871.—Henry Lee, Esq., President, in the chair. 
The following gentlemen were balloted for and duly elected :— 
Mr. Henry Moore, jun., and Mr. John Rickett.—Dr. Brarirawairte, 
Vice-President of the Quekett Microscopical Club, delivered a 
lecture “ On Mossks, WHERE THEY ARE TO BE FouND, AND HOW 
THEY ARE TO BE PreseRveD.” He pointed out that there were 
9,000 different species of mosses in the world, of which 540 were 
to be found in our own country. In all places where there was a 
constant mcisture, either locally or atmospherically, mosses would 
be found on trees, garden walls, thatched roofs, on rocks, or beside 
streams. Some were of an opposite character, preferring a scorched 
soil, hence they were frequently to be found on gipsy encamp- 
ments. One family of mosses flourished in decaying animal 
matter, another on old leather, such as discarded shoes, and a third 
even on old hats. In selecting mosses for the herbarium. it would 
be preferable to secure fruit-bearing specimens, keeping such species 
separate on a piece of numbered paper, and recording in a note-hoek 
the details respecting it for further reference. When travelling, 
and it was inconvenient to prepare the specimens at once, they 
should be spread cut on the floor to dry ; for, if packed close in a 
bag while in a damp state, they would mildew and spoil. When 
it was wished to prepare their specimens after having thus pre- 
served them, it would be necessary to soak them in water, which 
would free the roots from soil, and the plants would expand and 
become as fresh as when first gathered. It was best to form them 
into moderately flat tnfts. Scme of the leaves should be removed 
for microscopical examination, and mounted in glycerine jelly. 
Dr. Braithwaite exhibited numerous specimens from his own her- 
barium. For each family he had provided a sheet of cardboard, 
for each genus « sheet of coloured paper, and for each species a 
sheet of drawing-board. A minute description of the anatomy of 
mosses, and the important part they play in preparing the soil in 
many places for higher orders of vegetation, brought this interesting 
lecture to a close, when a hearty vote of thanks was unanimously 
accorded te Dr. Braithwaite. 
