270 
Life-history of Moniezia 
a corresponding species of intermediate host: for the sake of argument, let us 
say, with particular species of dung beetle (Aphodius), remembering in this 
connection that the invertebrate host is, probably, historically the earlier and 
was at one time, possibly, the only host. Nevertheless, we have to bear in 
mind the fact that several distinct species of Strongylus , for example, which 
all develop directly, often occur in the same sheep and occupy precisely similar 
positions in the gut. We can possibly explain this fact by assuming various 
species of Strongylus , or of Moniezia , to have become specialised originally 
in connection with distinct species of wild Ungulates and to have severally 
adapted themselves to the sheep later on, when it came under domestication. 
Whether or not, then, the fact that several distinct species of Moniezia occur 
in the sheep affords a clue to the nature of the life-history must be left to the 
judgment of the individual worker. 
Some experiments performed by Curtice as long ago as 1888 merit atten¬ 
tion, but they were unfortunately too loosely controlled and indecisive to 
furnish reliable conclusions. 
Neglecting complicating factors, we may say that Curtice was able to obtain 
infection among some of the lambs of a small flock under conditions such that 
“none of the invertebrates which are usually suggested as being the inter¬ 
mediary bearer were present.” The most important of these conditions were 
as follows: accommodation, a small stable with adjoining, very dry, hill-side 
pasture; food, clover and grain from the market; drinking water, from an 
adjacent well. Curtice, however, makes no mention of ectoparasites, some 
species of which, in the conditions of his experiment, might well have been 
responsible for conveying the infection, nor of coprophagous forms; in short, 
there is no real ground for his claim to have disposed definitively of the idea 
of an intermediate host. 
In 1893 Stiles reported only negative results from a series of experiments 
in connection with the life-history of Moniezia. These included attempts to 
produce direct infection by feeding eggs to sheep, and experiments to produce 
an intermediate stage in Melophagus ovinus, numerous coprophagous insects 
and earth-worms. He gave as his conclusion that some insect, worm or snail 
would eventually be found to contain the larval stage, and announced his 
intention of continuing the experiments on a larger scale. Apparently, no 
account of these later experiments was published. 
With regard to Melophagus ovinus , this ectoparasite had already been 
suspected as a carrier, and examined, by McMurrich (1884), in connection with 
a bad outbreak of tapeworm disease (M. expansa) in Manitoba. He found 
nothing incriminating. 
In 1915, Miss Lebour published an account of experiments she had con¬ 
ducted in feeding proglottids of Moniezia to the slugs Agriolimax agrestes and 
Avion circumscriptus. Her results were negative, the eggs, although readily 
ingested by the snails, failing to develop, and being recovered unchanged in 
the faeces. These were the last experiments previous to those of the writer. 
