204 BACTERIOLOGY 



perature. The growth quickly extends, but ceases after the 

 lapse of only a few days. 



Experiments have been carried on by Wertheim at the 

 clinic of Professor P. Schauta in Vienna, on the cultivation 

 of the gonococcus upon a medium consisting of a mixture of 

 two or three parts peptone glycerine agar and one part 

 human blood-serum. He obtains the latter from the blood 

 of the maternal portion of the umbilical cord, which is 

 severed but not ligatured, and the blood caught in sterilised 

 flasks. In this way Wertheim was enabled to grow 

 gonococci in plate-cultures, on which he was able to observe 

 colonies visible to the naked eye even after 

 twenty-four hours in the incubator. The 

 microbes grow rapidly, displaying their 

 characteristic forms and colour, and give 

 the best evidence of their specific action 

 by transmission to human beings. Wert- 



FlG. 79. — DEEP-LflNCi 



Colony of gonocoo- hcim s whole process vields astonishms 



ens ON A Sebtjji Agar a. ./ o 



Mmt ^'*"'""^ ^'^'^'" results, and according to his researches 

 growth takes place decidedly quicker 

 when deprived of oxygen than when the gas is admitted. 



The plate appears diffusely clouded in tAventy-four hours, 

 and assumes the appearance of a delicate floeculent layer 

 of moss. The majority of the colonies develop in the 

 substance of the medium, the deep ones appearing whitish- 

 grey by direct, yellowish-brown by transmitted light, and 

 in three days show a peculiar nodulation, which is so 

 regular as to recall the appearance of a blackberry (fig. 79). 

 The superficial colonies have a compact dot situated exactly 

 in the centre, which, when examined with a low power, 

 is found to correspond in structure with the deeper colonies, 

 but is surrounded on all sides by a superficial film which, 

 though at first very delicate, transparent, finely granulated, 

 and colourless, develops in three days round the central 



