ENTOZOA IN RELATION TO PUBLIC HEALTH, ETC. 287 
tion to certain remarks made in the final chapter, wherein 
the writer deals with the “ influence of sewage-farming on 
the public health.” In this place particular allusion is made 
to the discussion which followed Dr. Letheby’s paper, read on 
May 21, 1870, the author likewise referring to the brochure 
written by myself in 1864. 
Professor Corfield demands, and is entitled to demand, 
facts in support of the general conclusions which Dr. Letheby 
and myself have arrived at respecting the probable spread of 
entozootic disease by sewage irrigation ; and because the 
data which I have at various times advanced in this connec- 
tion do not happen to be of the very palpable kind that any 
ordinary observer may detect, he, somewhat imprudently, 
perhaps, gives prominence to the statements of Mr. Holland, 
w r ho, on the occasion of the discussion alluded to, expressed 
his belief “ that the danger of spreading disease by the irri- 
gation system was purely imaginary.” 
In order to estimate rightly the importance of this sort of 
criticism, it is necessary to consider the question from Mr. 
Holland’s point of view. For example, he finds that there is 
rio evidence of entozoal disease at Carlisle because, on “ asking 
whether the sheep had the rot,” he received a negative reply. 
Now, if Mr. Holland had possessed any acquaintance with 
helminthology, he would have known that “ rot” cannot be 
propagated by the sewage distribution of towms, for the 
simple reason that the inhabitants of our cities are not in- 
fested with the entozoon whose eggs indirectly give rise to 
that particular malady. Only in some seventeen or eighteen 
cases has the sheep-fluke been found in the human body ; 
nevertheless, other species and genera of the same family of 
entozoa are fatally endemic to their “ bearers,” amongst 
mankind, in certain countries. 
In the next place we are referred to Edinburgh, where, it 
is said, the cows, though fed with grass from the Craigen- 
tinny meadows for sixty or seventy years past, afford “ no 
evidence of the prevalence of disease among them.” That 
seems conclusive ; but in reply to this style of reasoning 
from negative data, let me tell Dr. Corfield, Mr. Holland, 
and others whose opinions have been so prominently put 
forward in this decision, that there is not, in my judgment, 
a single butcher or flesher in the United Kingdom who has 
ever either seen or, indeed, acknowledged the existence of 
measles in the cow, calf, or ox. 1 have asked butchers and 
other persons thus concerned whether they have ever wit- 
nessed parasites of this description in beef or veal, and they 
have not only protested that they never saw such things. 
