COCCACE^: AND THEIR PARASITIC RELATIONSHIPS 265 



cocci. The organism stains readily and is Gram-positive. Cul- 

 tures are readily obtained on all the common media and growth 

 occurs between 9 and 42, best at 37 C. Broth is diffusely 

 clouded with abundant sediment. In gelatin stab-culture, 

 growth occurs all along the line of inoculation 

 with funnel-shaped liquefaction (Figure 106). 

 On agar slant the growth is confluent and 

 yellowish after 24 hours. There is similar 

 growth on Loffler's serum, often with lique- 

 faction of the medium. 



The staphylococcus is relatively resistant 

 to heat and chemical germicides. It is killed 

 at 62 C. in ten minutes and at 70 C. in five 

 minutes. V. Lingelsheim 1 found it more resis- 

 tant, requiring ten minutes at 80 C. and an 

 hour at 70 C. to kill his strains, but his fig- 

 ures cannot be accepted without further con- 

 firmation. 2 It is about as resistant to chemical 

 poisons as any of the sporeless bacteria, and 

 is commonly employed as a test object in the 

 investigation of germicides. Mercuric chlo- 

 ride i- 1 ooo requires three to five hours to kill 

 staphylococcus cultures and much longer if 

 the organisms are present in pus. Carbolic FlG I0 6. Gelatine 

 acid, 3 per cent, kills them in two to ten culture staphylococcus 



aureus one week old. 



minutes. 



The pigment is a lipochrome and is produced only in the 

 presence of oxygen. The tryptic ferment diffuses out of the cells 

 and is capable of liquefying gelatin, albumen and fibrin. The 

 staphylococcus produces a soluble poison which kills leukocytes 

 (leukocidin) and others which dissolve red blood cells (staphy- 

 lolysin) and cause clumping of red blood cells (agglomerin) . 

 These substances are true soluble toxins and they are destroyed 



1 Neisser: Kolle und Wassermann, Handbuch, 1912, Bd. IV, S. 361. 



2 Compare with similar tests on streptococci by v. Lingelsheim, p. 262. 



