SKIN DISEASES . 685 



seborrhceic eczema, a non -liquefying micrococcus which forms 

 butyric acid has been isolated. 



Impetigo. The large vesiculo-bullous eruption of impetigo 

 contagiosa is caused by the Streptococcus pyogenes ; the small 

 pustule in the neighbourhood of hair-follicles, impetigo of Bock-- 

 hart, is caused by the M . pyogenes var. aureus. The B. diphtheriw 

 may also cause an impetigo (p. 328). 



Pemphigus. A diplococcus has been isolated in acute pem- 

 phigus by Demme, and in the chronic form by Dahnhardt. 

 Bulloch and Kussell Wells, in this country, seem to have isolated 

 an identical organism, and the following description of it is taken 

 from their papers. Cocci 0-8-1-5 /x in diameter, mostly arranged 

 as diplococci, and staining by Gram's method. On surface agar 

 the organism forms a thick, white, shining growth. In stab agar 

 the growth has a " nail-shaped " appearance. The colonies on 

 agar are at first round, but later, in seven days, they throw out 

 lateral projections and assume a rosette appearance. On gelatin 

 the growth is slow and slight, with some, but not marked, lique- 

 faction. On blood-serum the growth resembles that on agar. 

 On potato a whitish, semi-transparent film forms. Milk is 

 curdled. In broth it causes a general turbidity, with a whitish 

 sediment, and sometimes a pellicle, which soon sinks. Guinea- 

 pigs and mice inoculated or vaccinated with the organism died 

 in four to eight days, fine haemorrhages occurring in the lungs, 

 and the cocci being obtained from the blood. No bulla3 appeared 

 on the skin. The B. pyocyaneus may cause dermatitis and bullous 

 eruptions (see p. 285). 



The pyogenic cocci or their toxins may produce various bullous 

 eruptions, e.g. pemphigus neonatorum and contagiosus and 

 hydroa gestationis. 



Herpes zoster. Pfeffer observed bodies in the cells of the 

 vesicles which he believed to be protozoa. Gilchrist, however, 

 regards these merely as altered nuclei.. Streptococci seem 

 frequently to cause the condition (p. 177). 



FOOT AND MOUTH DISEASE. Various organisms have been 

 described in this disease. Loffler and Frosch determined that the 

 organism is ultra-microscopic and filterable. 



MASTOID DISEASE. See " Otitis Media." 



MEASLES. ^The cause of measles is unknown. The disease has 

 possibly been transmitted to monkeys but not to other animals. 



