108 HORSE AND CATTLE FLIES. 
ajter deposit, and also by opening the abdomen of various of the female 
flies at different dates before deposit,—that is to say, when the abdo- 
men had reached various degrees of enlargement. 
Thus he traced the pupal presence in the pupariwn back to the 
condition of ‘ bouillie blanchatre,” or whitish pulp, of which the micro- 
scopic powers of those days (in the case of the power used by Réaumur 
rather stronger than half-inch focus) were not sufficient to give the 
minutia of formation; also he traced back through its immediately 
earlier stages the presence of the white body presently to be deposited. 
His memoir on the H. equina is well worth studying, not only on 
account of the sound information given by the writer, which stands to 
this day as the original authority of much of what is most useful to us 
practically in our knowledge of this horse pest, but as an example of 
careful working forward of the matter under observation, and, where 
uncertainty arose, simply giving an exact description of what he saw, 
but leaving its nature as a subject for further investigation. 
Following on the same ground, and desiring (to use his own words) 
to verify for himself the admirable observations of his precursor, the 
well-known entomologist De Geer, on the 28th of July, 1770, com- 
menced a similar series of investigations, which, with their confirma- 
tion of Réaumur’s records, discussions of involved points, and some 
additions, as well as observations on the allied genus the Ornithomyia, 
will be found as referred to below.* 
Taking the main points of the development of the Pupipara within 
the abdomen of the female, it appears that the life-history may be 
shortly stated as follows. 
The young maggots (larve) develop, in the same way as those of 
other insects, from a fertilized egg; only in this case the hatching 
takes place inside the female, instead of after the egg has been laid. 
In the case of the Sheep Tick, or Spider Fly (the Melophagus ovinus), 
the egg is stated by Leuckart to be of a long and rather slender shape, 
the greatest length being somewhat over one millimetre (that is, the 
twenty-fifth part of an inch), and the breadth rather over half a 
millimetre. 
The abdomen is covered with a continuous membrane capable of 
great distension, which occurs in the females by reason of the larva 
feeding and growing within; this feeding being stated to be carried on 
by swallowing the secretion of large glandular appendages of the 
uterus. When full-fed the larva, of which there is only one (although 
the females are furnished with a pair of remarkable ovaries), is 
deposited in the shape of a soft whitish egg-like body (which answers 
* «Mémoires pour servir a l’histoire des Insectes,’ par M. le Baron Charles De 
Geer. Stockholm, mpccnxxy1. ‘Tome sixiéme, vi. Mém, 
