MICROCOCCUS GONORRHCEJE 349 



that have been successfully used for its cultivation this sub- 

 stance is apparently an essential constituent. By many inves- 

 tigators it is thought that only human blood possesses this 

 important ingredient, though this opinion is not universal. 1 



It was first isolated in culture by Bumm, who used for 

 this purpose coagulated human blood-serum obtained from 

 the placenta. 



Wertheim improved the method of Bumm by using a 

 mixture of equal parts of sterile human blood-serum and 

 ordinary sterilized nutrient agar-agar, the latter having 

 been liquefied and kept at 50 C. until after the mixture 

 was made, when it was allowed to cool and solidify. 



Other investigators have substituted for human blood- 

 serum certain pathological fluids from the human body, 

 such as ascites-fluid, fluid from ovarian cysts, and serous 

 effusions from the pleura and from the joint-cavities. 



The method used by Pfeiffer for the cultivation of bac- 

 terium influenzse (see that method) is also said to have been 

 successfully employed. 



Vedder's Medium. A simple medium that has given satis- 

 factory results in our hands is that devised by Vedder. It 

 consists of ordinary beef infusion agar (1.5 per cent, agar) to 

 which 1 per cent, of corn starch is added. The medium con- 

 tains neither sodium chloride nor peptone and has a reaction 

 corresponding to 0.2 to 0.5 per cent, acid to phenolphthalein. 



Wright's modification of Steinschneider's method has 

 given such satisfactory results in his hands that it will be 

 given here somewhat in detail. The medium consists of 

 a mixture of urine, blood-serum (human or bovine, either 



1 An instructive article on this subject is that by Foulertq-n, On Micro- 

 coccus Gonorrhcese and Gonorrheal Infection, Transactions of the British 

 Institute of Preventive Medicine, 1897, series i. 



