654 FILTERABLE VIRUSES— RICKETTSIA 
Berterelli and Cecchetto^ claimed to have reproduced trachoma in 
a Macaciis monkey with a filtrate (Berkefeld) prepared from a human 
case. NicoUe, Guenod and Blaisot^ were unable to infect monkeys, 
but stated that anthropoid apes were susceptible to the trachoma virus. 
Herzog^ believed that the "trachoma bodies" were involution forms 
of the gonococcus which, under certain unknown conditions, develops 
into very small forms that are indistinguishable from the trachoma 
bodies when they are within the epithelial cells. Herzog claims to 
have developed these very minute forms (microgonococci) in artifi- 
cial media through a series of rapid transplantations, and he states 
that this minute state in the development of the organism is the one 
which leads to trachoma. Williams^ has studied trachoma extensively 
and belicA'es that the cellular inclusions characteristic of trachoma are 
degenerated hemoglobinophilic bacilli. Xoguchi and Cohen^ have 
cultivated an organism from cases of conjunctivitis in which the 
inclusion bodies were present, and from an older case in which no 
inclusion bodies were found, which repeats in culture many of the 
important morphological appearances of the trachoma bodies. It is 
certainly neither a gonococcus nor a member of the group of hemo- 
globinophilic bacteria, but its identity with the trachoma bodies is 
not yet determined by its discoverers. Xoguchi and Cohen have 
made the important observation that the conjunctivae of certain 
monkeys are susceptible to infection with material containing the 
von Prowazek inclusion bodies, but not to the hemoglobinophilic 
bacilli isolated from cases of epidemic conjunctivitis; on the other hand, 
pure cultures of hemoglobinophilic bacilli cause an acute inflammation 
in the testes of rabbits; at certain stages of the infection numerous 
clumps of the organisms occur, which stimulate the von Prowazek cell 
inclusions. Injection of conjunctival scrapings containing the cell 
inclusion bodies alone is without effect in the rabbit. 
These observations have led Xoguchi and Cohen to conclude that 
a group of cases exists in which epithelial cell inclusions alone may 
be demonstrated in smears; pneumococci and hemoglobinophilic 
organisms are absent. The conjunctiva may become infected both 
with the inclusion bodies and hemoglobinophilic organisms. The sus- 
ceptibility of the conjunctiva of certain mcmkeys to infection with the 
hemoglobinophilic bacilli would appear to be an important method for 
diagnosis of the von Prowazek inclusion bodies. 
Smallpox (Variola) and Vaccinia.— Smallpox, (variola) and vaccinia, 
now generally regarded as an infection produced by the virus of small- 
pox modified by successive passages through the cow, are of unknown 
etiology. Ciuarnieri'^ has observed and described cell inclusions in 
• Centralhl. f. Bakteriol., orig., 190S, 47, 432. 
- Compt. rend. Aead. Soi., 1911, 152, 1504. 
•' Centralbl. f. Bakteriol., ref., 1910, 48, 276; Arch. f. Ophth., 1910, 74, 520; Ueber die 
Natur und Herkunft d. Trachomaerregers, Berlin and Wien., 1910. 
4 Arch. Opatholmol., 1918, 42, 506; Jour. Infec. Dis., 1914, 14, 261. 
s Jour. Exp. Med., 1913, 18, 572; 1915, 22, 304. 
6 Gentralbl. f. Bakteriol., 1894, 16, 299. 
