ON THE DEVELOPMENT OF BILHARZIA HjEMATOBIA. 751 
of the haddock ( Morrhua ceglefinus ) is neither more nor less 
than the juvenile condition of Gasterostoma gracilescens of the 
angler ( Lophius piscatorius) . After these indications, it is a 
sorry circumstance to have to state that all my experimental 
efforts yielded only negative results. I tried to induce the 
ciliated embryos to enter into the bodies of a great variety of 
animals, such as Gammari, Dipterous larvae, Entomostraca, 
Lymnaei, Paludinae, different species of Planorbis, and other 
fresh-water molluscs; but neither in them nor in Stickle¬ 
backs, Roach, Gudgeon, or Carp, did they seem inclined to 
take up their residence. These experiments, however, are by 
no means conclusive, since the conditions under which the 
experiments were made departed in several respects from 
those that are presumably essential to success in the ordinary 
course of nature. On what grounds, however, Dr. John 
Harley could possibly expect to rear Bilharzia by feeding 
dogs and rabbits with the ova, I am at a loss to understand; 
and his apparent suspicion that the parasites “ may increase 
in the [human] body from the development of the eggs” in 
a direct manner, is to me a mere haphazard conception, and 
one which virtually sets at nought the well-established expe¬ 
riences of every original experimenter whose name is known 
in connection with the advancement of helminthology in its 
ontogenetic bearings. Throughout the whole of Dr. Harley’s 
remarks on this head—and I confess to have had the greatest 
difficulty in comprehending the purport of many passages— 
the generally received opinion as to the necessity of an inter¬ 
mediary host amongst the Trematoda seems to me to have 
been altogether overlooked, and therefore to that extent 
utterly ignored. So far as Dr. Harley is concerned in this 
particular relation, the teachings of Leuckart, Pagenstecher, 
Guido Wagner, Siebold, Van Beneden, and especially Filippi, 
are altogether a dead letter. 
Appendix. —A most interesting circumstance connected 
with this case of Bilharzia lies in the fact that I obtained 
from the patient some other urinary parasites in the egg- 
condition. On five separate occasions, I obtained one or 
more specimens of the eggs or embryos of a minute nematode. 
In one instance, there were about fifty of these ova in the 
urine; their embryonic contents being well developed,and in 
a state of activity. Usually they were all in this advanced 
condition; but on the 25th of July, 1870, several were ob¬ 
served in much earlier stages of development. One of these 
was of a triangular form; its shape, granular contents, and 
fine limiting membrane, indicating separation from the ova- 
