424 



Drs. C. Shearer and H. W. Crowe. 



It has been recently pointed out by several observers that it is doubtful if 

 the polymorph leucocytes of the body are capable of successfully attacking 

 and digesting bacteria of the acid-fast group. It has been shown by 

 Tachernortusky* that extracts of these leucocytes, although containing the 

 usual proteolytic enzymes, are remarkably deficient in lipase. They are 

 probably unable for this reason to digest the waxy substance forming the 

 characteristic feature in the organisation of this group of bacteria. 



This is borne out by the work of Terry,* in Zinsser's laboratory, which 

 . shows that rat leprosy bacilli may be kept within the leucocytes for weeks 

 without undergoing any apparent change or losing their acid-fast properties ; 

 whereas the same bacilli, as shown by Zinsser and Cary,f are rapidly digested 

 when taken up by the spleen tissue cells grown in blood plasma. 



In the light of the foregoing observations, it seemed to us that it 

 should be possible to demonstrate experimentally the viability or non- 

 viability of the meningococcus within the leucocytes in cerebro-spinal 

 fever. The following experiments have been attempted with this object. 

 The recovery of living cocci from the leucocytes of undoubted cases of 

 cerebro-spinal fever ought conclusively to establish this point. 



Our first object is to show that we are using a medium which is quite 

 favourable to the growth of the meningococcus. Our experiments will give 

 erroneous results, if, for example, a medium is used on which the organism 

 will only grow when implanted in massive amount, for under such conditions 

 we are not certain that the germ is dead, although it fails to grow. The 

 tests should carry conviction on this point. 



The medium used in our experiments is that described by one of us.J 

 This is made from defibrinated bullock's blood and glucose, with trypsin 

 agar as a base. To avoid the cumbrous title " blood-agar-glucose," it will 

 be referred to briefly as " chocolate medium," from the similarity of its 

 appearance to this substance. 



To determine its power of growing the meningococcus, it was compared 

 with a number of media. The results of this comparison will appear in detail 

 elsewhere. Briefly, the conclusion is reached that if a 24-hour culture on 

 chocolate medium is emulsified in distilled water and diluted down and 

 planted out, then, presumably through a certain proportion of these germs 

 beino- dead, it is found that a certain minimum number of organisms are 

 necessary to the implantation for growth to take place. This minimum 

 varies with the different media in accordance with their capacity for 



* Quoted from Zinsser, ' Infection and .Resistance,' p. 284 (1914). 

 t Zinsser and Cary, ' Journ. Amer. Med. Ass.' (1912). 

 I Crowe, 1 Lancet,' November 21, 1915. 



