180 SUPPURATION. 



spinal canal at the autopsy. A large amount of the spinal 

 fluid should be used, as ordinarily it contains very few living 

 germs. 



Lumbar puncture : Have the patient lie on the right side, 

 with the knees drawn up and the left shoulder depressed, 

 the same position which he would assume when squatting 

 on his haunches. The site of puncture, the instruments, 

 and the operator's hands should be carefully cleansed and 

 disinfected. The needle should be of sufficient length 

 at least four centimeters, and have a long bevel. Locate 

 the interspinous space between the third and fourth lum- 

 bar vertebrae and insert the needle slowly, about one cen- 

 timeter to the right of the median line and directed slightly 

 upward and inward toward the median line. Pressure is 

 continued until the needle enters the subarachnoidean space, 

 which is made evident by the outflow of a few drops of cere- 

 brospinal fluid. About 5-15 c.c. of this fluid are collected 

 in sterile tubes. Care must be taken not to introduce the 

 needle too far, and not to draw blood, which interferes with 

 the examination. 



The needle must be introduced without any wiggling, and 

 when it meets with an obstruction it should be immediately 

 withdrawn and inserted again. The puncture is sealed with 

 collodion. Patients experience no ill eifects from this pro- 

 cedure. 



Diplococcus Lanceolatus. 



This organism is also known as Micrococcus lanceolatus. 

 Diplococcus pneumonice, and the pneumococcus of Fraenkel, 

 It is found in about 75 per cent, of all cases of lobar or 

 croupous pneumonia, and is accepted as the specific cause of 

 that aifection, although it has been manifestly impossible to 

 meet all the requirements of Koch's law as to specificity. 

 Its morphology is extremely variable, and hence its many 

 names (Fig. 78). 



Biology and morphology : The pneumococcus (as it is usually 

 designated) is an oval coccus which usually occurs in pairs. 

 Sometimes it forms short chains of four or five, when it may 

 be mistaken for the streptococcus. Each coccus has a leaf- 



