220 ELEMENTARY PHYSIOLOGY. [XXL 



2. Place a rat or guinea-pig under a bell-jar with 

 a sponge moistened with chloroform. When it 

 is thoroughly under the influence of the chloro- 

 form, quickly open the thorax, and cut across 

 the heart. Collect the blood in a glass beaker, 

 and defibrinate it; pour the defibrinated blood 

 into a platinum crucible surrounded by a mixture 

 of ice and salt. Leave it till it is frozen. Then 

 remove it from the ice and salt, so that it may 

 thaw. By this means the blood-corpuscles will 

 be broken up, and the blood will become laky 

 (cp. 1). If the blood does not become 

 thoroughly laky it should be frozen and thawed 

 again. 



Place the laky blood on one side in a cool place 

 (it is best to surround it with ice) for a day. 

 A sediment will then have formed consisting 

 partly of haemoglobin crystals 1 and partly of 



1 Blood crystals in quantity may be obtained in one of the following 

 ways : 



a. To defibrinated blood add ether gradually, shaking continuously 

 until the blood becomes laky (the volume of ether required is 

 about T V the vol. of the blood taken), place it then in the cool 

 for one to three days. Dog's blood treated thus often yields 

 crystals as soon as it is cooled. 



6. Blood is treated as in 3, but the washing is repeated many 

 times; to 10 c.c. of the crude solution of haemoglobin which is 

 obtained add strong spirit drop by drop; shaking continually 

 until a precipitate is obtained, note the amount of spirit added, 

 add this amount of spirit minus -5 c.c. to each 10 c.c. of the 

 rest of the haemoglobin solution, shaking well as the spirit is 

 added ; then place it in a mixture of ice and salt ; after some 

 hours to a day decant as much fluid as possible and filter the 

 remainder; the crystals on the filter may be washed with 

 30 p.c. alcohol and subsequently with water both at 0C. 



