A MANUAL OF PHYSIOLOGY 



injection is finished, draw off a sample of 5 c.c. of blood into a test- 

 tube labelled ' Peptone B/ and let it stand. In ten minutes collect 

 five further samples of 5 c.c. (' Peptone C, D, E, F, G '), and a 

 large one, H ; in half an hour another set of five small samples, 

 and at as long an interval as possible thereafter five more. Now 

 letting the dog bleed to death, observe that the flow of blood is 

 temporarily increased by pressure on the abdominal walls, which 

 squeezes it towards the heart, by passive movements of the hind- 

 legs, and also during the convulsions of asphyxia, which soon 



appear. Add to the peptone 

 blood D 5 c.c. of serum, to E a 

 little sodium chloride extract of 

 liver, to F a little extract of 

 muscle, and to G 15 drops of a 

 2 per cent, solution of calcium 

 chloride, and put C, D, E, F, and 

 G into a water-bath at 40 C. 

 Treat the other sets of small 

 samples in the same way. Note 

 how long each specimen takes 

 to clot, and report your results.* 



(8) Observe that the blood in 

 a, j8, and y has not coagulated. 

 Label four test-tubes ' Oxalate 

 A, B, C, D,' and put into each 

 about 5 c.c. of the oxalated 

 blood. Add to A and B 5 or 

 6 drops of a 2 per cent, solution 

 of calcium chloride, to C 12 

 drops, and to D as much as there 

 is of the blood. Leave A at the 

 ordinary temperature, put the 

 other test-tubes in a water-bath 

 at 40 C., and note when clotting 

 occurs. 



(9) To 10 c.c. of the fluoride 

 blood add a little more CaCl 2 

 than is required to combine with 

 the excess of fluoride present. 

 Label four test-tubes ' Fluoride 

 A, B, C, D,' and into each put 

 about 2 c.c. of this ' recalcified ' 

 fluoride blood. To B add i c.c. 

 liver extract ; to C i c.c. muscle 

 extract, and to D 4 c.c. water. 

 Label two more test-tubes ' Flu- 

 oride E and F.' Into each put 



2 c.c. of the fluoride blood without CaCl 2 . Add also to E i c.c. liver 

 extract and to F i c.c. serum. Put all the tubes in a bath at about 

 40 C., and observe in which and in what time coagulation takes place. 

 (10) By means of a centrifuge (Fig. n) separate the plasma 

 * Sometimes the injection of peptone hastens coagulation instead of 

 hindering it. It has been asserted that this is only the case when small 

 doses are used (less than 0*02 gramme per kilo of body-weight). But in 2 

 dogs out of 1 1 a dose of 0*5 gramme per kilo has been seen to hasten coagu- 

 lation, and in i out of 1 2 to leave it unaffected ; in the other 9 coagulation 

 was markedly retarded. 



FIG. ii. CENTRIFUGE (!UNG). 



The four cylinders shown at the top of 

 the figure are so swung that they become 

 horizontal as soon as speed is got up. 



