F. W. Flattely 273 
if the presence of the larval forms could be demonstrated microscopically in 
the udder of a ewe selected from what was known to be a regularly infected 
pasture. An opportunity to do this was afforded by the death of a six year 
old ewe at the farm under investigation. The udder was accordingly removed 
and a careful microscopical examination of it was made. Nothing was found 
in this way, which was perhaps only to be expected. Next, small snips of udder 
tissue were taken at various points, embedded and sectioned. For a time hopes 
were raised by the discovery in these sections of stages in the life-cycle of 
some organism or other encysted in the udder tissue. These cysts seemed more 
frequent in the portions of tissue taken high up the udder, in the neighbourhood 
of the larger branches of the lacteals and blood-vessels. They were thought 
to have some resemblance to hexacanth embryos. Examination under the 
highest powers of the microscope, however, failed to reveal any spines, which 
would definitely determine their character. What under the lower powers 
seemed to resemble spines turned out to be tears or folds in an internal mem¬ 
brane. I now hold the view that these are stages in the life-history of some 
Protozoan parasite. 
In pursuance of the same idea a quantity of milk from the ewes on this 
farm was examined microscopically, but failed to give anything of interest. 
This is obviously a very slow process and various methods of speeding it up 
were tried: evaporating, centrifuging, etc., but always without result. It was 
of considerable interest to notice that the small intestine of the old ewe already 
mentioned contained several tapeworms all of which were in a very ill-nourished 
condition, quite unlike those occurring in young lambs. How long the ewe 
had harboured these worms it is, of course, impossible to say. It is well known 
that infection with tapeworm only reaches serious proportions in young lambs: 
shepherds will say that they hardly ever notice proglottids in the faeces of 
oldei sheep and, similarly, butchers hardly remark the presence of worms in 
older sheep slaughtered at the abattoirs. Had these emaciated-looking worms 
hung on from the early period of the ewe’s life or were they acquired sub¬ 
sequently ? From the point of view of the life-history it is of capital importance 
to establish whether infection is contracted only in the period before the lamb 
is weaned or continuously all through life. If the latter is the case then it 
would effectually dispose of the idea that the lamb acquires infection through 
its mother, and the fact that the worms are so much less often observed in older 
sheep would simply mean that the conditions for the development of the tape¬ 
worm aie then less favourable, owing to the substitution of an herbivorous 
diet for one of milk. Speaking of the occurrence of M. expansa in the United 
States, Cooper Curtice (1890) says that 
the worm, though present throughout the year, is more abundant in the locality of Wash¬ 
ington during May and June than at any other season....In Colorado an outbreak was heard 
of in a flock of Merinos which occurred annually about July and August, after which the 
lambs would improve. The disease is more prevalent in the summer season, and causes the 
greatest damage in lambs less than six months old. If the young animals can be carried beyond 
this age they seem to be either better able to withstand the ravages of the parasite, or 
