6tj ENTOZOA OF RATS AND MICE. 



(1803) and Galli-Valerio (1905) carried out experiments to 

 determine manner of infection. Bossuet (1902) summarised 

 RailUet's finding. 



Railliet's results are of interest. He placed some eggs 

 obtained from a mouse liver in a moist chamber early in 

 March, 1885, segmentation commencing in June. By the 

 end of that month some eggs contained embryos and by the 

 middle of July these were present in most of them. After 

 four months incubation {i.e., at the end of July) some were 

 fed to two rats and in five days afterwards one of these animals 

 died, free embryos being found in the caecum and Hver. 

 The other rat died two months later, i.e. seventy-five days 

 after ingesting the eggs and the liver was found to be invaded 

 by worms, tumours and egg masses being present. 



In another series of experiments, eggs were taken in 

 the middle of October, 1885, incubated for 26 months 

 i.e., until December 1887. Segmentation was apparent in 

 some in June 1886 {i.e., eight months later), embryos 

 appearing between July and December, 1886. Some of 

 these embryos containing eggs were kept until December 



1887 (seventeen months after the embrj^os had appeared 

 in them) when they were fed to two white rats. In February 



1888 one died in a state of emaciation, its liver being found 

 to be heavily infected Avith Trichosomes, but no eggs were 

 present. The second rat was killed in December, 1888, but 

 its liver was quite unparasitised. 



In a third series, Railliet took some eggs in- 

 cubated in October 1885, and fed them to a white rat 

 in December 1888, after having been three years and 

 two months incubationg, and two years and five months 

 after embryos had been formed in them. This rat was 

 killed ten weeks later (Feb. 1889), its liver being found to 

 contain Trichosomes devoid of eggs. 



He showed that eggs removed from water for two 

 days but kept in a moist room, still underwent development 

 but five days' drying in air prevented it. Four months 

 dessication (December to April) killed the eggs or 

 embryos. 



Bancroft, in 1891, fed rat-Uvers containing eggs to white 

 rats and recovered eggs unchanged in the faeces. The 



