ON SEWAGE AND PARASITES, ETC. 
357 
entozoon in the bodies of various kinds of intermediary hosts, 
I have, nevertheless, succeeded in rearing and watching the 
habits of the larva in the condition of an actively-swimming, 
cone-shaped, ciliated, infusorial animalcule, furnished with a 
highly developed water-vascular system. Finally, let me add 
that, contrary to all expectation — and as affording a result 
somewhat unfavorable, perhaps, to the view’s I have hitherto 
advocated — the larvae of this entozoon develop more rapidly 
in pure w 7 ater than in fluids which contain impurities of any 
kind; so that, in short, w r e may say that the young of 
Bilharzia cannot arrive at their ultimate destination, in the 
bodies of mankind and monkeys, until the urine or sewage 
in which they occur shall have been more or less considerably 
diluted v r ith fresh or salt w’ater, in either of w 7 hich media, 
my recent experiments, thus far, prove that they are capable 
of developing themselves with extraordinary rapidity. 
In concluding, I may observe that since the preceding, 
remarks were penned I have received a new 7 and interesting 
illustration of the fact that entozootics amongst animals are 
constantly overlooked, even w 7 here the parasites occur in con- 
siderable numbers. I refer to the prevalence of Stephanurus 
dentatus in the sw r ine of the United States, the particulars of 
which curious discovery I have already communicated to the 
last week^s number of the British Medical Journal (January 
14). Finally, also, let me add that I have not by any means 
attempted or desired, on the present occasion, to treat the 
subject before us exhaustively. I shall, how’ever, have accom- 
plished all that was proposed if, in the judgment of the Asso- 
ciation, I shall have succeeded in demonstrating the high 
probability, not to say the certainty, of a large increase of 
parasitism amongst mankind and animals, as arising from the 
distribution of fresh sew 7 age by the method of irrigation on 
an extended scale. 
ON SEWAGE AND PARASITES, ESPECIALLY IN RELATION 
TO THE DISPERSION AND VITALITY OF THE GERMS 
OF ENTOZOA * 
By T. Spencer Cobbold, M.D., &c. 
After the considerate manner in which my previous paper 
was received by the Association, I now 7 venture to submit a 
few further details, which may be regarded as supplemental 
to the data supplied by the former communication; and in 
selecting the present order of facts, I have been guided partly 
* Read February 18tli, 1871. 
