45 
and I have never found them in any but very young maggots. 
The material is chitinous, or horny, and the possession by the 
young worm-like maggot of this ap¬ 
paratus for cutting or tearing is of 
considerable interest in connection 
with the first minute track down 
the hide, to the embryo maggot 
below, having been to all appearance 
cut or torn. 
The various successive forms and 
conditions of maggot-life as observed 
in this country , in the case of what is most especially the “ British 
Ox Warble Fly,” the Hypoderma bovis of De Geer, are as follows. 
The first consists of the passage of the worm-like larva to the 
under side of the hide, where, at this stage, in the small inflamed 
patches or swellings it lies free, that is to say, not inclosed in a 
cell or thickened tissue, merely in a small bloody sore, in which 
by the colour of its contents it may be seen to be feeding on the 
bloody matter. This changes, as above mentioned, to a more 
pear-shaped form, placed with the smallest end (containing the 
minute horny spiracles at its tip) uppermost, and thus with the 
compact hard-tipped apparatus above, and the growing body 
behind, is well calculated to force open and enlarge the passage 
down which it came (see preceding figs.).* 
The size and shape of the perforation through the hide altered 
progressively with the growth of the maggot. At first this passage 
was very little larger at the lower than at the upper opening; and, 
though the walls of the perforation had now become smooth and 
shiny, I could not distinguish the presence of any distinct lining 
membrane. With the enlargement of the passage its shape became 
more cone-like (corresponding with the altering form of its tenant); 
* At the above stages the power of inflation of the maggots by absorption 
of fluid is very remarkable. In my own experiments I found that by placing 
them in glycerine and water (in which they would live for as much as eighty 
hours) they became inflated until they were shiny almost without trace of the 
segments, and so hard that it was almost impossible to compress them with the 
fingers. I had not the opportunity of seeing whether this inflation takes place 
in the living hide, but, if such is the case, as the maggots would thus form 
what may be called “ living and growing plugs,” quite capable of pressing back 
the tissues from around them, or from before the small hard tip, but not subject 
(so long as they continue inflated) to being themselves compressed; this power, 
whether used instinctively or automatically, might be a great help in forcing 
the little maggot tail uppermost (as we find it) to the surface of the hide,/row 
which it had previously torn its way head foremost downwards.—E. A. 0. 
