62 A MANUAL OF PHYSIOLOGY 



through the first with a smaller degree of dilution than through the 

 second. Examine the laked blood with the microscope for the 

 ' ghosts,' or shadows of the red corpuscles. The addition of a drop 

 or two of methylene blue will render them somewhat more distinct. 



(2) Put some blood in a test-tube, or flask; cork up, and let stand 

 till it begins to putrefy. It becomes laked. 



9. Globulicidal Action of Serum. (i) To a small quantity of 

 rabbit's blood add an equal volume of dog's serum. Mix and let 

 stand for fifteen or twenty minutes. The colour of the blood is now 

 darker than before, and it can be seen to be laked. Examine 

 microscopically. 



(2) Place a small drop of rabbit's blood and a somewhat larger 

 drop of the dog's serum on a slide, near, but not quite in contact 

 with, each other. Now put on a cover-slip, so that the drops just 

 come together, and examine at once with the microscope with a 

 moderately high power. Where the two drops mingle, the red 

 corpuscles will be seen to fade out, leaving only their * ghosts.' A 

 few of the corpuscles which come into contact with the, as yet, 

 undiluted serum may be entirely dissolved. 



(3) Heat some of the dog's serum to 60 C. for ten minutes, and 

 repeat (i) and (2). No effect will now be produced on the rabbit's 

 corpuscles. 



(4) Repeat (i) and (2) with dog's blood and rabbit's serum. The 

 blood will not be laked. 



10. Blood-pigment (i) Preparation of Haemoglobin Crystals. 

 (a) Heat some dog's blood to 60 or 65 C. in a water-bath for about 

 ten minutes, taking care that the latter temperature is not exceeded. 

 Cool, and examine the oxy haemoglobin crystals with the microscope. 

 They form long rhombic prisms and needles. 



(b) Add a little crude saponin to dog's blood in a test-tube. Shake 

 up well, and allow it to stand till the colour becomes dark. Then 

 shake vigorously, and a mass of haemoglobin crystals will be formed. 



(c) Put a small drop of guinea-pig's blood on a slide. Mix with a 

 drop of Canada balsam and cover. Tetrahedral crystals of oxy- 

 haemoglobin will soon form. The slide may be kept. 



(2) Spectroscopic Examination of Haemoglobin and its Derivatives. 

 (a) With a small, direct-vision spectroscope look first at a bright 

 part of the sky. Focus by pulling out or pushing in the eyepiece 

 until the numerous fine dark lines (Fraunhofer's lines), running 

 vertically across the spectrum, are seen. Narrow the slit by moving 

 the milled edge till the lines are as sharp as they can be made. Note 

 especially the line D in the orange, the lines E and b in the green 

 and F in the blue. Always hold the spectroscope so that the red is 

 at the left of the field. Now dip an iron or platinum wire with a loop 

 on the end of it into water, and then into some common salt or sodium 

 carbonate, and fasten or hold it in the flame of a fishtail burner. On 

 examining the flame with the spectroscope, a bright yellow line will be 

 seen occupying the position of the dark line D in the solar spectrum. 

 This is a convenient line of reference in the spectrum, and m 

 studying the spectra of haemoglobin and its derivatives, the position 



