276 PATHOGENIC BACTERIA. 



yellowish-brown central nucleus about which a flat, 

 rounded disk spreads out. The edges may be dentate ; 

 the color is grayish or yellowish near the centre, becom- 

 ing less intense as the thin edges are reached ; the for- 

 mation is finely granular. 



The vitality of the culture is low, and when cultivated 

 the cocci tend to die out readily, ceasing to grow when 

 transplanted after eight or ten days. It becomes neces- 

 sary, therefore, when studying the organism to trans- 

 plant it frequently — Park says every two days. 1 



The organism can be secured for cultivation either 

 from the purulent matter of the exudate found at 

 autopsy, or from the fluid obtained by lumbar puncture. 

 To obtain this fluid Park gives the following directions : 

 " The patient should lie on the right side with the knees 

 drawn up and the left shoulder depressed. The skin of 

 the patient's back, the hands of the operator, and the 

 large antitoxin syringe should be sterile. The needle 

 should be 4 c.cm. in length, with a diameter of 1 mm. for 

 children, and larger for adults. The puncture is gener- 

 ally made between the third and fourth lumber vertebrae. 

 The thumb of the left hand is pressed between the 

 spinous processes, and the point of the needle is entered 

 about 1 cm. to the right of the median line and on a 

 level with the thumb-nail, and directed slightly upward 

 and inward toward the median line. At a depth of 3 or 

 4 c.cm. in children and 7 or 8 c.cm. in adults the needle 

 enters the subarachnoid space, and the fluid flows out in 

 drops or in a stream. If the needle meets a bony ob- 

 struction, withdraw and thrust again rather than make 

 lateral movements. Any blood obscures microscopic 

 examination. The fluid is allowed to drop into abso- 

 lutely sterile test-tubes or vials with sterile stoppers. 

 From 5 to 15 c.cm. should be withdrawn. No ill-effects 

 have been observed from the operation." 



In making a culture from this fluid Park points out 

 that as many of its contained cocci are dead, a consider- 



1 Bacteriology in Medicine and Surgery, 1899, p. 518. 



