BY T. HARVEY JOHNSTON. 67 



animals were killed several months later but no worms were 

 found. Healthy rats living in cages with infected ones 

 did not become infected. Eggs kept in water had not 

 undergone segmentation after a period of three months, 

 but when examined after fifteen months immersion, were 

 found to contain coiled embryos which by gentle pressure 

 on the coverglass were easily expelled from the eggs. 



Six weeks later (August, 1892) mature eggs were fed 

 to white rats and in three weeks produced serious symptoms 

 — dyspnoea, emaciation and diarrhoea. One was killed 

 and the other died (Sept. 1892) the hver of both being very 

 heavily infected with worms, eggs being in abundance. 

 When large numbers of eggs were fed to rats, the latter 

 died in from three to four weeks, but if only a small numl er 

 was given, the animals recovered and an examination of the 

 liver some months later showed the organ to be normal 

 except for the presence of the whitish egg masses. The 

 eggs ultimately die and undergo calcification in the li\'er, 

 this being noted in the case of an animal six months 

 after a light experimental infection, when many of the 

 eggs were found to be calcified. They never produced 

 abscesses. Bancroft stated that they do not j^ass to the 

 intestine by the bile duct. 



Exposvire of the eggs in water to sun'ight destroyed 

 them. Eggs were placed in the shade in water in July 

 1892 ; six weeks later there was no aj)parent change ; five 

 weeks later segmentation had begun ; in six weeks more, 

 the embyro worms began to be outlined ; and in three weeks 

 more {i.e., five months from the date of commencement of 

 the experiment) the embryos were mature, but even then 

 consideral)le pressure was needed to cause them to be 

 liberated from the egg shells. The embryos were able to 

 maintain vitality within the shells in water for over eighteen 

 months. 



Experiments to determine the route of the embryos 

 after their entry into the digestive canal were not successful. 

 He found that in a fortnight immature worms could be found 

 in the liver. 



During 1909 and 1910 I carried out a series of experi- 

 ments with the eggs. Some were taken from Ej). alexand- 



