might be concluded from the perusal of the 
litterature. 
There is also a bagshaped gastro-inte s- 
tinal organ, easily perceived when full of 
yolk granules. lt communicates with the mouth 
by a wide tube which narrows towards the 
anterior end. The wall of this tube and of 
the sac are apparently flaccid. 
On both sides of the stomach, a large 
glandular cell is easily seen, but 1 am not 
able to recognise in living specimens the nu- 
cleus, generally indicated in drawings. The 
excretory tube begins wide and narrows un- 
til it reaches the cephalic papilla where it 
bends outwards. When full, the glands and 
excretory ducts are very clear, the former 
may be turned inwards and cover the gas- 
tric sac. In fig. 15 glands and sac are not 
very full and show distinctly at the same 
level; the gland-cells are not granulated, as 
one might expect from some drawings of 
the embryo of Sch. haematobium. 
I am unable to perceive clearly the ner- 
vous system, as it appears in some drawings. 
However, I see, under the organs just de- 
scribed andnearly in the centre, one large ve- 
sicular cell and a few smaller ones. 
Their function seems like the one of a 
small balloon inside of a large one, giving 
to the body the rigidity and elasticity neces- 
sary for the movements. The rest of the body 
is formed by larger and smaller spherical 
masses; they are not very well defined and 
represent undoubtedly the germina! cells. 
The outer and inner cilia only begin to 
move when the egg is in a liquid medium 
and the water penetrates by osmosis, as 
happens when the eggs are isolated by wa- 
shing with fresh water. 
Ecdysis and free life of the embryo or 
miracidium. 
(Fig. 15—17.) 
The favourable conditions for the ecdysis 
consist in pure water, light and a tempera- 
ture near to 30° C. In Rio de Janeiro there 
are many winter days which are not suited 
to its observation and in cooler climates the 
117 ——— 
natural conditions with rare exceptions are 
unfavourable. 
The best process for observing the free 
life of the miracidium consists in washing, 
straining and sedimenting stools comparati- 
vely rich in eggs. The sediment with little 
water is poured in small glass dishes and 
exposed to the sun. The same result may be 
obtained by approaching an electric bulb, suf- 
ficiently to raise the water temperature to 300. 
Even in the best of conditions, when the 
first miracidia appear soon, the ecdysis is 
never seen in all of them, probably because 
a certain number has nct yet reached com- 
plete maturity. Keeping the rest in a cooler 
and less lighted place, the experiment, repea- 
ted once a day, still gives positive resulis in 
the next three or four days. Even after eight 
days, eggs with living embryo may be found 
but no ecdysis takes place. 
Before the ecdysis we note the penetra- 
tion of the water followed by a dilatation of 
the shell. The vitelline granules show lively 
molecular movement and all the cilia and vi- 
brating membranes begin to play. Then we 
note from time to time an energetic contrac- 
tion of the embryo which may turn comple- 
tely inside the shell. The ecdysis is momen- 
tary and therefore easily missed. In one of 
my observations, it was proceded by very 
rapid and energetic rotation of the embryo 
which took a nearly globular shape. 
The empty shell shows a spindle-shaped 
tear (which generally passes through its 
equator) and its aspect is quite as striking 
and characteristic, as that of the entire egg. 
After leaving the egg, the miracidium 
stretches, taking a cylindrical form, and swims 
in large curves towards the light, until it 
is held back by the margin of the dish. With 
strong, oblique illumination itis easily recogni- 
zed by its characteristic movement. (Confusion 
with certain infusoria and rotatoria must be 
avoided.) At a less favorable temperature the 
embryo becomes more pyriform and sinks to 
the bottom. The same happens, if several 
hours pass without its finding a suitable host. 
Enclosed in capillary glass tubes and 
exposed in a refrigerator to very low tem- 
