32 BLOOD CORPUSCLES. 



to let down the bottle. The carbonic acid gas in the chamber 

 is easily replaced by air, by aspiration through the tube a. 



Action of Carbonic Acid Gas. The preparation having 

 been brought into focus, the gas is allowed to pass through 

 the chamber for a short time. At first, the only observable 

 effect is that the nuclei of the slightly smoother disks are more 

 distinct. If the carbonic acid is now replaced by air, the nuclei 

 again become indistinguishable. We have to do, therefore, 

 with a transitory coagulation of the substance surrounding 

 the nucleus. An excess of the gas brings the nuclei perma- 

 nently into view. If, however, we first add to our preparation 

 a quantity of water, sufficient not merely to swell the colored 

 disks, but to deprive them partly of their color, the result is 

 somewhat different. After a short action of the gas, the ap- 

 pearances are much as they have been already described ; but, 

 if an excess is admitted, bodies similar to the zooids above 

 described as produced by the action of boracic acid, come into 

 view. 



Instead of the pale oblong nuclei, the areas of the decolor- 

 ized disks inclose relatively large, yellow, roundish bodies, both 

 the areas and the inclosed bodies being beset with fine gran- 

 ules. In those disks which have previously lost their color, 

 and are consequently scarcely visible, the nuclei become visi- 

 ble after the addition of excess of carbonic acid, as pale 

 granulous bodies, the disks themselves also containing nume- 

 rous granules. If we now replace the carbonic acid by air, 

 the corpuscles recover, in every respect, their previous aspect; 

 those in which the zooids had come into view becoming smooth, 

 and of uniform color, so that neither nucleus nor granules can 

 be distinguished. Those disks which have lost their color by 

 the action of water become, as before, uniformly pale and in- 

 distinct. The experiment may be repeated several times. It 

 is not difficult to explain all these appearances by coagulation. 



It is a very good plan, in order to study the action of car- 

 bonic acid on newt's blood, in all degrees of dilution, to 

 examine a salt solution preparation of such blood on the mov- 

 able stage (Fig. 2), which also serves the purpose of a gas 

 chamber. On warming the metal rod, water vapor is disen- 

 gaged from the floor of the chamber (into which a drop of 

 water has been previously introduced), and acts upon the cor- 

 puscles. 



In order to study the action of carbonic acid on the colored 

 corpuscles of man,^ it is best to employ a drop of blood mixed 

 with salt-solution, taking care that the individual cells are as 

 much as possible separate from one another. If, as soon as 

 the corpuscles become horse-chestnut shaped in consequence 

 of the action of the salt-solution, the preparation is subjected 

 to the action of the gas, we at once observe that the acuminate- 



