309 



I have often found in the early stages of development, both in solid and 

 liquid media. It consists in a more or less hexagonal plaque, in the centre 

 of which is seen a well-stained coccus, surrounded by a light-coloured zone, 

 dotted along its margin by five, six or seven cocci like the centre one, their 

 protoplasm showing or not signs of segmentations. The macroscopic 

 characters and the size the colonies of the tetracoccus, as well as its 

 chromegenous properties, are very variable, — even more so than Dr. 

 Sternberg has pointed out: its colour, for instance, may vary from a pure 

 white to a canary yellow, with the intermediate tints already mentioned 

 by that author. After several day 's growth in tubes of broth, the tetracoccus 

 produces a viscous substance, which may be drawn out in elastic filaments, 

 and is deposited at the bottom of the tube ; but on moving the latter around 

 its axis the viscid mass rises like a dirty yellow string, with its more or less 

 wide base attached to the bottom, while the elongated conical portion seen 

 in the liquid ends in a point or fringe^ — the whole presenting a rather 

 typical appearance. 



The cultures of the tetracoccus in broth emit a peculiar characteristic 

 odour. With regard to its resistance to heat I have been able to sterilize a 

 culture, a few days old, by immersion of the test tube in water at 65° C. 

 during half an hour; but this proved insufficient to sterilize a balon 

 containing an older culture. I therefore suspect that some of the elements 

 are more resisting than others; there may be spores. The most favourable 

 temperature for the growth of the microbe is between 35° and 40° C. 



In order to obtain the tetracoccus versatilis, I usually employ one of 

 the two following methods : — One consists in the introduction into a tube 

 of peptonized broth, to which 5 per cent, of glycerine has been added, of a 

 droplet of blood from the finger of a yelllow fever patient at the beginning 

 of the second paroxysm (between the third and the fifth day). The following 

 precautions must, however, be observed in order to secure the germination 

 of the microbe : — 1st. A patient must be chosen whose blood be not already 

 sterilized by the use of internal antiseptics, such as the benzo-naphthol, 

 especially if the urine be already smoky; and, 2nd, strong germicides, such 

 as mercuric bichloride or carbolic acid, must be avoided in the washing of 

 the site of puncture. I wash the pulp of the ring finger with soap and 

 w T ater, then with pure water, and finally with absolute alcohol, keeping the 

 skin covered with cotton soaked in alcohol, while I prepare the needle, 

 pipette, and tubes of broth. Before puncturing the skin, I dry it with 

 sterilized cotton. The tubes thus planted do not always germinate; but, 

 with these precautions, I have this year obtained the tetracoccus in one 

 or both of the tubes of glycerine broth that I usually inoculate. 



The other method consists in applying to a patient (under the 

 conditions already mentioned) a mosquito of the diurnal species, with 

 white rings on its legs (Culex mosquito — Robineau Desvoidy). At the end 

 of two or more days the insect is asphyxiated by means of a few drops 



