34 Observations on Cosmarium Margaritiferum. 
the contents of the inner bag had so much distended them- 
selves, that the bead-like margin of the outer case was lost.* 
In this figure I have represented as accurately as possible, 
the appearance presented on November 12th. On this plant 
I noted — " The motion very active, and the plant apparently 
in a healthy condition. The outer membrane quite plain, 
but certainly the same plant as the others. When fresh 
water was introduced around the object, the outer membrane 
remained immoveable, while the inner was pushed into a 
globe. The granules escaped one night, and the plant as- 
sumed much the appearance of fig. 10." In the following 
spring I figured fig. 5, which appeared to me early develop- 
ment of the masses of swarming granules ; and fig. 2, 
which, in the same month (February 1852), was the most 
usual appearance and colour, becoming darker and fuller as 
the spring advanced. In the summer of 1851, I applied 
iodine to fig. 3, when the granules ran with extreme rapidity 
into four balls, as represented in fig. 7 ; I also tried to find 
out their nature by pressing them out of the plant. In this I 
was unsuccessful, as the contents mingled rapidly with the 
other vegetable forms in the water. I satisfied myself, how- 
ever, that they escaped at the centre of the plant, from which 
part the contents escape to form the sporangia, as I afterwards 
discovered. As I frequently found plants resembling fig. 4, 
I concluded that when the plant was mature the granules 
escaped of themselves. 
In September 1851, I had the pleasure of observing ano- 
ther change in these beautiful plants. At one o'clock the 
two hemispheres of a plant separated, as figured in fig. 11 ; 
the transparent hemispheres protruded between the original 
halves, containing only colourless granules. At six o'clock, 
the four parts were nearly equal in size, and the green matter 
evenly divided, though faint in colour. At eleven next 
morning, the whole had assumed a healthy, vigorous appear^ 
ance, as at fig. 12. Soon after, a restless motion was visible ; 
and at twelve o^ clock the plants were freeing themselves from 
an enclosing membrane (13), which had first appeared in 
fig. 11. At one o'clock the plants had escaped, and moved 
freely off into the surrounding water, leaving their old enve- 
lopes, which, in the following spring (1852), when my plants 
were very healthy and active, I found in great numbers in the 
water. I suppose that the time taken on this occasion (twenty- 
* This observation is an important one, if it be quite sure that the 
specimen observed was C. margaritiferum : it may be questioned, how- 
ever, whether it was not a specimen of C. Ralfsii, which had found its 
way amidst the others. — W. B. C. 
