8 STROMA LAKE- COLOURED BLOOD. 



.stained. Magenta causes one or more small spots or maculae to appear on the edge 

 of the corpuscles (fig. 7, a). What its significance is, is entirely unknown. Normal 

 saline solution (0-6 per cent. NaCl), tinged with methyl violet, is a good staining 

 and preservative agent.] 



[Agitation with Mercury. If ox blood be shaken up with mercury for 7 or 8 hours, the cor- 

 puscles completely disappear, no trace of stroma or corpuscles being found in the fluid [Meltzer 

 and //',/,/,. The addition of pyrogallic acid (20 per cent), potassic chlorate (6 per cent.), 

 and silver nitrate (3 per cent), completely prevents dissolution of the corpuscles, even though 

 the shaking be kept up for fourteen days.] 



If blood be mixed with concentrated gum solution, and if concentrated salt solution be added 

 to it under the microscope, the corpuscles assume elongated forms. Similar forms are obtained 

 by mixing blood with an equal volume of gelatine at 36 C, allowing it to cool, and then 

 making sections of the coagulated mass. The corpuscles may be broken up by pressing 

 firmly on the cover-glass. Iu all these experiments no trace of an envelope around the cor- 

 puscles is observed. [An excellent reagent for " fixing " the blood-corpuscles is either a dilute 

 solution or the vapour of osmic acid.] 



Conservation of the Corpuscles. In investigating blood with the microscope for forensic 

 purposes, it is necessary to have a solvent for the blood when it occurs as stains on a garment 

 or instrument. Dried stains are dissolved by a concentrated, or a 30 per cent, solution of 



Fig. 7. 

 a, b, human red blood-corpuscles ; a, acted on by magenta ; b, by tannic- acid. The others are 



amphibian red blood-corpuscles ; c, d, e, effect of tannic acid ; /, of dilute acetic acid ; y, of 



dilute alcohol ; d, by boracic acid {Stirling). 

 caustic potash, or with one of the preserving fluids. If the stain be softened with con- 

 centrated tartaric acid, colourless corpuscles are specially distinct (Struwe). Nevertheless, 

 corpuscles are often not found in such stains. If the corpuscles have become very pale, 

 their colour may be improved by adding a solution of iodide of potassium, a saturated solution 

 of picric acid, 20 per cent, pyrogallic acid, or 3 per cent, solution of silver nitrate. 



5. STROMA LAKE-COLOURED BLOOD Many reagents cause the haemo- 

 globin to separate from the stroma. The haemoglobin dissolves in the serum ; the 

 blood becomes dark red and transparent, as it contains its colouring matter in 

 solution, and hence it is called " lake-coloured" (Rollett). The aggregate condition 

 of the haemoglobin is not altered when the corpuscles are dissolved it only 

 changes its place, leaving the stroma and passing into the serum. Hence, the 

 temperature of the blood is not lowered thereby. 



Methods. To obtain a large quantity of the stroma for chemical purposes, add 10 vols, of 

 a solution of common salt (1 vol. concentrated solution, and 15 to 20 vols, of water) to 1 vol. 

 of defibrinated blood, when the stromata are thrown down as a whitish precipitate. 



For microscopical purposes, mix blood with an equal volume of a concentrated solution of 

 sodic sulphate, and cautiously add a 1 per cent, solution of tartaric acid. 



The following reagents cause a separation of the stroma from the haemoglobin, and thus make 

 blood transparent : 



(a) Physical Agents. 1. Heating the blood to 60 C. (SchttUze) ; the temperature, however, 

 varies for the blood of different animals. 2. Repeated freezing and thawing of the blood 

 (llollctt). 3. Sparks from an electrical machine (but not after the addition of salts to the 

 blood) (Rollett) ; the constant and induced currents (Neumann). 



(b) Chemically active Substances produced within the Body. 4. Bile (Huncfcld), or bile salts 

 (Plattncr, v. Ihisch). 5. Serum of other species of animals (Landois) ; thus dog's serum and 

 frog's serum dissolve the blood-corpuscles of the rabbit in a few minutes. 6. The addition of 

 lake-coloured blood of many species of animals (Landois). 



(c) Other Chemical Keagents. 7. Water. 8. The vapour of chloroform (Bottchcr) ; ether (v. 

 ll'iftich); amyls, small quantities of alcohol (Rollett); thymol (Marchand) ; nitrobenzol, 



ethylic ether, aceton, petroleum ether, &c. (L. Levin). 9. Antimoniuretted hydrogen, arseni- 

 uretted hydrogen ; carbon bisulphide ; boracic acid (2 per cent.), added to amphibian blood, 

 causes the red mass (which also encloses the nucleus when such is present), the so-called 



