278 
Life-history of Moniezia 
e ggs passed by the ewes. A number of invertebrates were collected from this 
meadow: Aphodius punctato-sulcatus, A. ater, Aleocharis , dung-flies (Scato- 
phaga stercoraria), earth-worms ( Lumbricus terrestris), and carefully dissected 
in the laboratory (the earth-worms were sectioned), but without result. 
During the spring of 1919 and again in the spring of 1920 it was determined 
to test the possibility of dung beetles acting as carriers more thoroughly. 
From the farm above discussed, and from another in the same neighbourhood 
which also had a history of infection, over a hundred individuals of Aphodius 
(various species, mostly A. punctato-sulcatus, but also A. prodromus , A. ater 
and A. rufipes, about three-score Staphylinids ( Aleocharis lanuginosa), a score 
of dung-flies (S. stercoraria) were collected and dissected, all without result. 
The following experiment was also performed: 
A number of dung beetles, mainly A. punctato-sulcatus , were kept among 
sheep faeces liberally sprinkled with tapeworm ova, for a period of several 
weeks. The faeces were spread upon turf in the open and covered by a rect¬ 
angular frame 18" x 18" x 5" with a top of narrow-meshed wire gauze, the 
sides of the frame being sunk a couple of inches into the grass. Under natural 
conditions, the beetles do not occur either in perfectly fresh or in comparatively 
stale dung since they require time in order to locate and enter the dung, and 
vacate it when it begins to dry up. Consequently it was necessary to remove 
the stale dung periodically and to substitute fresh dung which was also, of 
course, sprinkled with eggs. At the end of three weeks most of the beetles 
still present were removed and dissected under the microscope. Occasional 
eggs were detected in the gut of some of the beetles, but nothing in the nature 
of an intermediate stage was found. A few further beetles were collected from 
the faeces subsequently but they too gave negative results. Altogether some 
20 beetles were dealt with in this way. This was only a small fraction of the 
beetles originally present in the faeces, a number having died or escaped. 
Another set of observations in Aberdeen was directed towards ascertaining 
the effect of long exposure to weather upon the eggs of Moniezia. Short series 
of proglottids were scattered upon a medium of (a) pure, washed sand, and 
(b) garden soil contained in seedling boxes, and exposed to the weather from 
early October till shortly before Christmas. The boxes were covered with 
perforated zinc through which the rain had free access; they had the usual 
arrangements for drainage but were lined at sides and bottom with a double 
layer of the finest bolting cloth to prevent the eggs from being washed away. 
A further lot of isolated proglottids were placed in a jar full of tap-water 
(c) covered with fine bolting cloth which was left in the open under the same 
conditions as the boxes. 
Notwithstanding that the season was a fairly wet one the proglottids in 
both boxes (a) and ( b ), when examined after nearly three months were dis¬ 
tinctly desiccated. They had not so much decomposed as shrunk to a thin film. 
The effects were more marked in the case of those which were lying on sand. 
The eggs recovered from these proglottids by teasing in water were in the case 
