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puscles. A drop of water being placed in the well, and 
the blood on the under surface of the covering-glass closing 
it in above, the temperature is gradually raised by means 
of a spirit-lamp applied to the copper wire, and the aqueous 
vapour thus produced condenses on the glass. Thus the 
observer can watch the gradual addition of water to the 
sides of the drop of blood. ‘The effect on the frog’s blood- 
corpuscle is very remarkable, and has been described by 
Stricker, who does not, however, give figures of the corpus- 
cles. As the plasma gradually becomes diluted, some of the 
corpuscles are seen to float about, and at first become oat- 
shaped, assuming sharper extremities than the normal form 
(fig. 5 a); then they gradually become spherical (fig. 5 8, c). 
If the addition of water is continued the corpuscles discharge 
their hemoglobin, and, finally, with excess, appear to break 
up more or less, becoming irregular stromata, in which a large 
clear nucleus can generally be seen. 
Human red corpuscles, treated in the same manner, become 
globular, not swelling, as has been asserted, of the action of 
water, by some writers, but simply changing their propor- 
tions. ‘They finally with excess discharge their colour, and 
become irregular stromata, retaining a definite spherical out- 
line if the action has not been rapid. 
9. Effect of carbonic acid gas.—Stricker, who states that 
the object of his experiments was to ascertain the effect of 
the alternate action of carbonic acid and atmospheric oxygen 
on the red blood-corpuscles, found that on fresh normal 
corpuscles a stream of CO, introduced into the gas-chamber 
has no effect. But when the corpuscles have been previously 
acted on by aqueous yapour, as described above, to the 
extent that they have assumed the spherical form, a re- 
markable action is obtained. 
In the case of the frog the nucleus immediately becomes 
sharply granulated (see fig. 6 a). Stricker then proceeds 
to pass atmospheric air into the gas-chamber in place of the 
CO,, and the granulation of the nucleus at once disappeared 
(fig. 6 6), and the corpuscle assumed once again an elongated 
shape. This change of shape is very strange, and not 
readily accounted for ; the granulation of the nucleus is due, 
as pointed out by Schweigger-Seydel and Schmidt, to pre- 
cipitation of paraglobulin, which is redissolved on removal of 
the carbonic acid. The nucleus can thus be made to come 
and go by alternate steams of CO, and atmospheric air several 
times; but after the first change of form from the spherical 
condition they retain the elongated shape. After a time 
the “starred” condition of the body of the corpuscle is 
