648 FILTERABLE VIRUSES— RICKETTSIA 
is an indistinetiveness of outline, which contrasts sharply with the 
distinctness of outline of bacteria. In addition to these minute lanceo- 
late organisms, slender, bacillus-like bodies — some of which exliibit 
bipolar staining— are occasionally demonstrable. They are of about 
the same length as the lanceolate bodies, and are very similar to those 
found in the intestinal tracts of infected ticks. In the later stage of 
development in the tick, the parasite appears as a small, faintly 
staining rod with more deeply staining chromatoid granules (Giemsa 
stain). These bodies are found in both the larval and adult stages 
of the insect. Wolbach has shown that this organism is always intra- 
cellular, both in mammalian and tick tissues; it may be intranuclear 
in the latter. The name Dermacentroxenus rickettsi is proposed by 
Wolbach as the name for the parasite. Cultivation experiments were 
uniformly negative. 
DISEASES OF UNKNOWN ETIOLOGY. 
Measles.— The etiology of measles is unknown, but Hektoen^ 
produced the disease in two susceptible individuals by injecting 
blood from a patient exliibiting typical symptoms. The blood was 
removed about thirty hours after the appearance of the eruption, and 
the disease induced was clinically perfectly typical. Anderson and 
Goldgerger- report a successful inoculation of several monkeys with 
blood from human cases in the eruptive stage; 4 out of a total of 
9 animals developed a febrile reaction and a limited eruption. The 
virus was not carried in the desquamated epithelium. The virus 
was carried through three monkey generations in one experiment. 
Growth was not obtained in artificial media heavily inoculated with 
blood from patients, shoMii by experiment to contain the virus. 
Buccal and nasal secretions contain the virus of measles which passes 
a Berkefeld filter.^ Tunnicliff^ has reported the cultivation of a small 
micrococcus in anaerobic, semi-coagulated horse serum and blood- 
ascitic fluid-glucose agar cultures. Successful isolations were made 
in the preemptive and eruptive stages in a large percentage of cases. 
Somewhat later in the disease a rather large number of these cases 
showed a variety of bacteria. 
The organism passed an N. Berkefeld filter, and gradually became 
aerobic during successive transfers. A green color developed around 
colonies in blood agar, and the organisms fermented glucose and 
saccharose. Inulin was untouched. Mannitol and lactose were fer- 
mented by a few strains. All were bile insoluble. The organism 
appears to belong to the Streptococcus viridans group. Serum from 
patients showed a diminution in opsonic power, followed by a rise 
' Jour. Inf. Dis., 1905, 2, 2.38. 
2 Public Health Reports, 1911, 26, 847, 887. 
' Goldberger and Anderson: Jour. Am. Med. Assn., 1911, 57, 476, 971. 
* Jour. Am. Med. Assn., 1917, 63, 1028; Jour. Infec. Dis., 1925, 37, 19.3. 
