110 J. B. CLELAND. 
GAMASIDS AND TicKs.—On Sydney rats, during 1909, 
1910 and 1911, Harvey Johnson found 287 gamasids (Le- 
laps)—260 of them in 1909; 12 ticks (Ixodide); and 6 
very small acarids, mites, probably the above L. bacott. 
NoOcTDRES ALEPIS Raillet et Lucet (Sarcoptes muris). 
—This causes a warty scabies, affecting the ears and genital 
organs. Such warty ears are not uncommon in Sydney rats. 
Johnston’ has recorded the mite for H. norvegicus in New 
South Wales and ££. rattus (alexandrinus) in Western 
Australia. 
The Protozoal Parasites of Rats and Mice. 
TRYPANOSOMA LEWISI (Kent).—Though trypanosomes 
were first observed in the blood of the trout in 1841, and 
_ various observations had later been made on species found 
in mammals, frogs and fishes, they received little attention 
until 1878. In this year, Lewis, in India, described the 
species found in Mus decumanus (Kpiymys norvegicus) and 
in Mus rufescens. In 1881, Saville Kent named this para- 
site Herpetomonas lewist. The name of Lewis is especially 
associated with the beginning of the enormous amount of 
work dealing with all aspects of trypanosomiasis, because 
his discovery of the trypanosome of the rat was soon follow- 
ed, in 1880, by that of the first definitely pathogenic species, 
the trypanosome of surra found by Evans in horses and 
camels in India. Some 20 years later, in 1901 and 1902, 
trypanosomes were found in cases of sleeping sickness in 
man. This discovery, followed later by proof of these try- 
panosomes being responsible for the disease, led to attempts, 
by means of arsenic compounds and synthetic dyes, to kill 
the parasites without injuring their host. From these 
partially successful results emerged eventually the dis- 
eovery by Ehrlich of salvarsan, and the employment of this: 
2 Johnston, Rep. Govt. Bur. Microbiol., Sydney, 1909 (1910), p. 81. 
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