REPORT OF THE BUREAU OF ANIMAL INDUSTRY. 183 



and received into the corral. The tsenise of Nos. 107, 109, 108, and 

 106 coincide with this; but the lambs No. 109 and 108 also point to a 

 later infection, as many very small tsenise were found in them. No. 

 108, which had tsenise l cm long six weeks after its receipt in Wash- 

 ington, would lead us to suspect a recent infection; but this is not 

 necessarily the case, as the influence of the rumen of the sheep in 

 detaining the parasite for a length of time has yet to be learned. 

 The absence of young tsenise measuring less than 7 cm in No. 106 at 

 sixteen weeks after its last association with an animal containing 

 adult tsenise, and twenty weeks after its arrival in Washington, is 

 also of interest, in that it points to infection of the lamb from the 

 adult sheep associated with it. No. 110 shows a very slight infection, 

 and one, judging from the age of the tsenia3, that could have occurred 

 in Colorado. 



The six cases show a slow growth of the parasite; they also point 

 to one of two things : that the taenise are, as embyros, retained in the 

 rumen for som e time after bei ng swallowed, or that these tseniae are 

 continually infecting their hosts by the direct method. That is, the 

 embryos passed by sheep pass with little or no preparation into other 

 sheep and develop without the intervention of an intermediary host. 

 So far I have found nothing to absolutely prove or disprove the lat- 

 ter statement. The infection, as shown by the various sizes found in 

 these lambs and other sheep, points to a continuous infection nearly 

 all the year. (See Tables A, B, and C.) 



Nos. 106 and 110 indicate a cessation of the infection for the length 

 of time it required the smallest (7 cm ) to attain their size. Lamb A 

 indicates the time to be something less than twenty weeks, or at the 

 period when they were received at Washington. Nos. 106, 107, 108, 

 and 109, which had been confined eleven and twelve weeks, show a 

 great infection, as great as I have seen. This would happen with 

 animals which were being infected in confinement, for the opportu- 

 nities of infection, if the infection should prove to be direct, are 

 greater. Various conditions, as the weather, food, water, etc., have 

 so much to do with the problem of infection, that far more data are 

 necessary. 



The fact of slow development and continuous infection are the 

 main points brought out in this experiment. Continuous infection 

 is naturally one of the results where tsemae are constantly develop- 

 ing and shedding ripe prog] ottides laden with embryos for the infec- 

 tion of other hosts. Continuous infection also leads me to suspect 

 that no intermediary host is necessary for the continuance of the 

 life of the embryo. This proceeds from the fact that no single species 

 of mollusk, insect, or other animal is to be found at all seasons and 

 places necessary to suit all the conditions under which we find the 

 host infected. 



Experiment No. 2. A lainb dropped at a slaughter-house in this city was kept 

 with its mother in an uninfected stall. 



The lamb was fed on January 10, 1887, with a large quantity of proglottides of 

 Tcenia expansa, from No. 108. The embryos were found to be alive and moving 

 before feeding. 



On March 20 I fed the same lamb w th proglottides. of T. fimbriata from No. 

 103. These contained live embryos on the 18th instant. 



On March 29 1 fed the same lamb with proglottides containing embryos of T. fim- 

 briata from No. 101. 



Killed it April 19, 1887, and found nothing except a few white spots in and on 

 the liver. The experiment had no results. 



