290 ENTOZOA IN RELATION TO PUBLIC HEALTH, ETC. 
this source. Thus, a sow in which I reared some fifteen 
or sixteen millions of trichinae never displayed any symptoms 
of pain, nor did the animal lose its appetite for a single day. 
When slaughtered, the flesh appeared so healthy to the naked 
eye, that bystanders refused to believe that the animal was 
diseased, one assistant, even after microscopic evidence, 
desiring to remove portions, as a perquisite, for home con- 
sumption. In point of fact, he succeeded in carrying off the 
heart ; and I understood that he ate part of it. As I have 
said, young animals do not bear infection so well as old ones ; 
and thus, in the case of the three pigs infected by Dr. 
Thudichum, two became ill, whilst the third died. These 
“ hosts, ” respectively, were u less than three months old.” 
Rats and rabbits appear to resist the action of the flesh-worm 
migrations very successfully, and the same may be said of 
cats and dogs. In the case of one full-grown cat, however, 
I had great difficulty in restoring the animal, the acuteness of 
trichiniasis depending upon an extreme degree of infection. 
The style in which some unscientific opponents write is 
scarcely creditable to them. Thus, Mr. C. F. Gower, in 
criticising Dr. Letheby’s paper (as it appeared in the Ipswich 
Journal of August 27, 1870), accuses Dr. Letheby of talking 
“ a little at random about measly meat,” and asks if the 
parasitic ova might not be “ discoverable adhering to the 
blades” of grass, in cases where irrigation has been em- 
ployed. Mr. Gower evidently thinks that the ova of entozoa 
measuring less than the -^-o" in diameter ought (if our views 
be true) to be picked up by those who visit “ sewage-irrigated 
grounds” with as little difficulty as the country folks experi- 
ence when they hunt up plovers’ eggs at the proper season. 
In short, Mr. Gower’s long and vigorous letter in the Ipswich 
Journal betrays a want of knowledge of the rudiments of 
entozoological science. 
I may in the next place observe that it is not very surprising 
that the general public should disregard any warnings uttered 
respecting the probable increase of parasitic disorders from 
sewage irrigation, since, as obtains in the case of many other 
evils, no one thinks of demanding an investigation until a 
readily recognised calamity occurs. It will be said, in reply, 
that the absence of any palpable evil is a proof that there is 
no need of inquiry. This is the very point 1 am disputing. 
Take the case of trichina. Is it not perfectly clear that, but 
for Dr. Zenker’s discovery that fleshworms “ were capable of 
giving rise to a violent disease in the human body,” we might 
have remained ignorant of the disorder, as such, to the present 
day? It is extremely improbable that the entozoal character 
