92 Mr. E. Ponder. The Hcemolytic 



Table VI. 



When t = 18. 



5. 



Time after preparation. 



5 minutes. 



1 hour. 



12 hours. 



24 hours. 



100 



l i minutes 



2J minutes 



18 minutes 



40 minutes. 



200 



2 „ 



30 



20 „ 



15 



300 



1 minute 



4k » 



4 „ 



3 



400 



50 seconds 



50 seconds 



1 minute 



H 



600 



40 „ 



50 „ 



1 



1* » 



1000 



2 minutes 



3 minutes 



7 minutes 



8 



All blood suspensions exhibit this change, some in greater degree, some in 

 less. The change is not one merely to be detected with care, but a very 

 obvious one, which makes investigation into this subject very difficult, much 

 experience being necessary to correctly interpret results. It will be seen 

 from this Table — which gives a typical result — that the freshly prepared 

 suspension is rapidly hsemolysed by all the concentrations of glycocholate, on 

 the addition of the serum albumin, it may be therefore termed " sensitive." 

 An old suspension, however, is not rapidly hsemolysed except by dilutions of 

 glycocholate in the neighbourhood of 1 in 500 ; it may, therefore, be called, 

 compared to the fresh suspension, an " insensitive " suspension. This meaning 

 will be attached to these terms in the following pages. 



At this point it will be convenient to deal with one essential difference 

 between a sensitive and an insensitive suspension. When a standard blood 

 suspension is prepared, blood is drawn into citrated saline, to prevent 

 coagulation. The suspension is centrifuged, the cells washed thrice with 

 saline, and the cells then added to normal saline (0"95 per cent. NaCl), to 

 form a 5 per cent, suspension. This suspension is normally sensitive. If the 

 blood be drawn into normal saline instead of into citrated saline, and the act 

 of coagulation thus permitted, an insensitive suspension results after washing 

 the cells, and preparing the suspension in the same way as before. This is a 

 constant occurrence ; the act of coagulation seems to determine that the 

 suspension shall be insensitive. If the blood be drawn slowly from the 

 finger and clotting thus be allowed to begin, the resulting suspension will be 

 insensitive. This very interesting fact is of use ; for, with reasonable care, a 

 sensitive suspension can always be prepared, and also if an insensitive suspen- 

 sion be required, it can with certainty be made. 



The changes through which a sensitive suspension goes on standing are 

 very curious ; further investigations, to be noted below, throw some light on 

 these changes, It may be observed that there is no difference between a 



