16 THE CIRCULATING LIQUIDS OF THE BODY 



some other unknown substance, or more probably bound in some 

 solid or semi-solid combination to the stroma, and rilling up the 

 space within the envelope in the interstices of the spongework. 

 Since there is good reason to believe that the haemoglobin as 

 obtained artificially from the corpuscles is not quite the same sub- 

 stance as the native blood-pigment within them, the latter is some- 

 times distinguished by a separate name haemochrome. To the 

 physical properties of the stroma it is usual to attribute the great 

 elasticity of the corpuscles that is, the power of recovering their 

 original shape after distortion for their elasticity is in no wise 

 impaired by the removal of the haemoglobin. 



Rouleaux Formation. When blood with disc-shaped corpuscles is 

 shed, there is a great tendency for the corpuscles to run together into 

 groups resembling rouleaux, or piles of coin. No satisfactory explana- 

 tion of this curious fact has yet been given. 



Crenation of the corpuscles, a condition in which they become 

 studded with fine projections, is caused by the addition of moderately 

 strong salt solution, by the passage of shocks of electricity at high 

 potential, as from a Leyden jar, or by simple exposure to the air. Con- 

 centrated saline solutions, which abstract water from the corpuscles 

 and cause them to shrink, make the colour of blood a brighter red, 

 because more light is now reflected from the crumpled surfaces. On 

 the other hand, the addition of water renders the corpuscles spherical; 

 more of the light passes through them, less is reflected, and the colour 

 becomes dark crimson (Frontispiece). 



The White Blood-Corpuscles, or Leucocytes. The red corpuscles 

 are peculiar to blood. The white corpuscles may be looked upon 

 as peripatetic portions of the mesoderm (see Chap. XIX.), and some 

 of them ought not in strictness to be called blood-corpuscles. They 

 are more truly body corpuscles. Similar cells are found in many 



situations, and wan- 

 der everywhere in the 



A. ^ B. f c spaces of the connec- 



tive tissue. They pass 

 into the bloodvessels 

 with the lymph, and 

 may pass out of them 

 again in virtue of 

 their amoeboid power. 

 They consist of proto- 

 Fig. 2. Amoeboid Movement. A, B, C, D, succes- P la ? m > less differ- 

 sive changes in the form of an amoeba. entiated than that 



of any other cells in 



the body, and under the microscope appear as granular, colour- 

 less, transparent bodies, spherical in form when at rest, and 

 containing a nucleus, often tri- or multi-lobed. Many of the leuco 

 cytes of frog's blood at the ordinary temperature, and of mam- 

 malian blood when artificially heated on the warm stage, may be 



