MICROCOCCUS TETRAGENUS 455 



and a tough pellicle forms on the surface, and a quantity 

 of flocculent matter collects at the bottom of the tube. 



Agar-Agar. — A white opaque moist expansion is formed, 

 which afterwards becomes dry and furrowed. 



Potatoes. — A moist, cream-like expansion forms over the 

 whole surface. 



Micrococcus Tetragenus. — This organism was first obtained 

 by Koch and Gaffky from a cavity in the lung from a case 

 of pulmonary phthisis. It has since been found frequently 

 in normal saliva and in tubercular sputum. It occurs as 

 small micrococci, about 1 ft, in diameter, which divide in 

 two directions, forming tetrads, which are enclosed in a 

 transparent, jelly-like envelope, which are especially well- 

 developed in the animal body, but not so well in cultures. 

 It stains quickly with the ordinary stains, when from the 

 animal body the envelope may sometimes be seen feebly 

 stained. It also stains by Gram's method. Subcutaneous 

 inoculation of a culture in minute quantity into mice is 

 fatal in from two to six days. The cocci are then found to 

 be very numerous in the spleen, lungs, liver and kidneys. 

 Cultural characters : 



Gelatine Plates. — Small white colonies are developed in 

 from twenty-four to forty-eight hours. When these are 

 examined under a lens they are seen to be finely granular, 

 with a mulberry-like surface. 



Gelatine Tubes. — A thick white or yellowish-white ex- 

 pansion is formed. The gelatine is not liquefied. 



Agar-Agar. — The growth at first may consist of a series 

 of spherical colonies, which afterwards develops into a 

 spreading expansion. 



Potatoes. — A viscous milk-white growth is formed. 



Bacillus Tholoeideum. — This organism occurs in the in- 

 testinal tract, and is, therefore, invariably found in sewage 



