746 ON THE DEVELOPMENT OF BILHARZIA MMATOfllA. 
rest between the sessional periods, more, indeed, than can 
safely he devoted to inaction. 
A longer period of study may hereafter be found necessary 
to enable the student to properly grasp the subjects which 
will be brought under his notice. Meanwhile, the fact that 
the time is short furnishes the strongest argument against 
wasting any portion of it. 
Extracts from British and Foreign Journals. 
ON THE DEVELOPMENT OF BILHARZIA HiEMATOBIA; TO¬ 
GETHER WITH REMARKS ON THE OVA OF ANOTHER 
URINARY PARASITE (THE SO-CALLED TRICHINA CYS¬ 
TICA OF DR. SALISBURY) OCCURRING IN A CASE OF 
HEMATURIA FROM NATAL. 
By Professor T. Spencer Cobbold, M.D., F.R.S., 
Lecturer on Botany, Parasites, and Parasitic Diseases at the Royal 
Veterinary College. 
(Continued from p. 646). 
It is also noteworthy that the development of the larva is 
equally well accomplished in distilled water, in well-water, 
and in brackish water; whereas in pure sea-water the process 
goes on somewhat less satisfactorily. It was found, indeed, 
that the addition of slightly saline water to ciliated embryos, 
which were on the point of expiring in fresh water, had the 
effect of reviving them for a time. These facts, as we shall 
see presently, have an important practical bearing; but in 
the meantime I have to observe that the actual mode of escape 
of the embryos is by no means the slow process that Bilharz 
has described. Almost invariably the shell bursts by a longi¬ 
tudinal slit extending over fully two thirds of its long dia¬ 
meter ; the first point of rupture being commonly situated 
midway between the spine and the centre of the shell. In 
normal births, so to speak, the head of the animalcule 
emerges first; but occasionally the animal escapes sideways 
(Fig. k ), and I have even seen the embryo extricate itself tail 
foremost. Not unfrequently it has a difficulty in detaching 
itself from the shell, in which case the latter is whirled round 
and round by the half-freed prisoner. The lodgment of the 
beak against any foreign substance, under such circumstances, 
