644 ON THE DEVELOPMENT OF BtLHARZIA HA5MATOBIA. 
times readily distinguishable from the ordinary sarcodic 
elements of the body properly so called (Fig. g). The sar- 
code-globules refract light strongly; and, when the larva is 
not compressed in any way, they move freely within the 
somatic cavity. In well developed embryos, whilst still in 
the egg, the cilia are observed to clothe every part of the 
larva except the oral papilla. This minute nipple-like pro¬ 
jection measures about the 1-3000th of an inch transversely, 
forming a very simple kind of unarmed proboscis. When 
the head of the free embryo is viewed from above, the pro¬ 
boscis looks like a central ring surrounded by a series of 
regular folds, which radiates outwards like the spokes of a 
wheel. The ridges thus formed support numerous cilia; 
these latter projecting at the circumferential margin of the 
cephalic cone in such a way as to present the figure of a 
star. Dr. Harley has given an admirable representation of 
this character, which is shared by many other parasitic larvae. 
Throughout the greater part of the time, whilst the embryo 
is still resident within the egg, the broad neck or base of the 
cephalic cone forms a fixed point of resistance by its firm 
attachment to the inner wall of the shell; and this structural 
union, so long as it remains intact, enables the embryo to 
move not only its head and body from side to side synchro¬ 
nously, but also each part quite independently. When the 
time for final escape is drawing near, the vigorous move¬ 
ments of the cone-shaped head seem chiefly concerned in 
loosening the membranous connection just referred to; and 
when, at length, the ciliated animalcule has succeeded in 
overcoming this first difficulty, it is almost ludicrous to wit¬ 
ness its frantic efforts to find an opening in the shell. While 
thus partially liberated, it will rush to and fro from one pole 
of the egg to the other, performing a series of summersaults, 
and at the same time occasionally rolling itself over laterally. 
This activity becomes gradually more and more violent, until 
at length its apparent excitement seems to be worked up into 
a sort of frenzy. I have many times watched these remark¬ 
able performances, which, however, are only to be seen within 
those ova whose shells, for some reason or other, refuse to 
yield to the earlier and ordinary efforts of the prisoner. In 
all cases where these remarkable phenomena are witnessed, 
the eye readily detects a number of small free globules 
between the embryo and the inner wall of the shell (Fig. k). 
These minute particles are likewise tossed about tumultu¬ 
ously during the rapid rotatory movements of the imprisoned 
larva. Except as regards their size, these globules do not 
differ in character from the sarcodic contents of the animal- 
