8 QUATERCENTENARY STUDIES IN PATHOLOGY 



not the amboceptor which is most markedly influenced by the injection 

 of leucocytosis-producing substances. 



Bulloch has also shown that the inoculation of sodium cinnamate 

 raises the complement content, but leaves the haemolytic amboceptor 

 quite uninfluenced. 



We shall refer later to the bearing of these facts on the experimental 

 results obtained by us, and which are presently to be detailed. 



Technique of Experiments. 



The effect of all substances employed in the production of leucocytosis, 

 was tested both on rabbits and guinea-pigs, the inoculation being made 

 intraperitoneally in the case of the latter, and either intravenously or 

 intraperitoneally in the case of the former. In the former, also, the 

 subcutaneous method was once or twice employed. Immediately before 

 the inoculation, samples of blood for counting purposes (total and 

 differential leucocyte counts), and estimation of opsonic content of serum, 

 were drawn from the posterior auricular vein. In the guinea-pig one 

 occasionally has a little difficulty in obtaining satisfactory amounts of 

 blood from the ear, but, with some practice, one can usually obtain quite 

 a large supply by making a smart puncture in the vein situated close to 

 the margin of the ear, and exercising a little pressure. At the same time 

 blood was also drawn from another animal, to act as control in the 

 estimation of the opsonic index in the experimental animal. Whenever 

 a sample of blood was drawn from the experimental animal during the 

 period of observation, a similar sample was drawn from the control 

 animal. In many cases this was found to be unnecessary, as we shall 

 show {cf. infra). 



The blood counts were made by the usual haematological methods. 

 For the opsonic determinations the technique recommended by Wright 

 was carried out as follows : — 



1. The blood sample was collected in a glass capsule with a recurved 



limb. When coagulation had set in, the tube was hung in 

 a centrifuge, which brought about the separation of the clear 

 serum. 



2. In most cases the leucocytes employed were of human origin, and 



were obtained by allowing the blood to run into a glass capsule 



(328) 



