Dr. Johnson's .observations 
18 
common. They are at first of a greyish white colour, # 
but in ten or fifteen minutes become of an amber colour, b b . 
They differ much as to size, but are usually about three lines 
in length, and two in breadth, convex above and flattened 
beneath. The dark points (Fig. 8, a a) mark the openings 
left in the capsule by the manner in which the leech deposits 
it, and are those places from which (the resistance there 
being less than in any other part) the young escape. They 
are deposited during the whole of the summer months, and 
even so late as the month of October ( 99th ) , and contain 
each from six to twelve ova ; which are well defined as to 
figure, being perfectly round, and have a smooth uniform 
appearance. The ova, and the enveloping membrane are 
represented, magnified, in Fig. 8. In about a fortnight the 
ova are much increased in size, and show rough edges 
(Fig. 9.) In three w ; eeks, they take the form of an oblong 
oval (Fig. 10), when animal existence is, for the first time, 
developed : which consists, in simply an elongation and con- 
traction of the body. At this period, there is little or no 
resemblance to the parent animal. In six weeks, the young 
are completely formed, and in active motion about to quit the 
capsule. Fig. 11 shows the included young at this period. 
It is not a little amusing to witness their exertions to escape 
from their imprisonment. They contract themselves, as it 
respects their length, into as small a compass as possible, 
and then forcibly push forward the head, butting, as it were, 
at the dark point of the capsule to effect their escape. After 
many efforts, they succeed in making a small opening, 
through which they endeavour to force a passage. I have 
frequently watched them, the head having free motion 
