FORMATION OF MEMBRANE. Xlll 



Mr. Macadam gave me details of appearance of the maggots reminding 

 "him of cattle-bots " ; these he destroyed in boil or warble-like 

 swellings, simply as we often do here, by excluding air, and drew up 

 the description of the pain as being that of "an ordinary sore plus the 

 intense itching." 



Independently of effects on the constitution of inflammation, and 

 ulceration (when cattle-attack is on a large scale), it certainly cannot be 

 desirable, if their sensations are like those described, that even on a 

 small scale they should be troubled by the pain of sores plus the intense 

 itching, and also _/jZ((s (what our warble-maggots have quite structural 

 appliances to cause) pain, at ti))ies "quite sharp, as if the maggot was 

 screwing itself round in its hole." 



Formation of membrane or false-skin over surface of icarble-hole or cell. 

 Coincidently with the alteration in size, position, and condition of 

 the maggot, and especially on the power of keeping up a constant 

 irritation by means of the muscular contraction and expansion of its 

 prickly skin, there are changes in the state of the surface of the cell in 

 the lower part of the hide, and also of the surface of the passage up 

 the warble swelling, which are of the greatest importance to tanners, 

 and all connected with sale of hides. At a certain stage, instead of 

 the surfaces being torn and raw, or presently, in part, of a glass-like 

 smoothness, a distinct pellicle or skin-like membrane begins to form, 

 covering the walls of the perforation or warble-hole, and also, and 

 continuously with it, the greater part of the surface of the maggot-cell. 

 The beginning of March is the earliest date at which I have myself 

 found the lining pellicle observably forming, but the date must 

 obviously vary with circumstances. 



On the 3rd of March, 1884, Messrs. Hatton, of Hereford, favoured 

 me with a piece of heifer hide, less than six inches square, containing 

 twelve or more warbles, which had now 

 advanced in growth, so as to show on the 

 flesh side of the hide as well-defined 

 lumps, ranging from three- to five-eighths 

 of an inch across, and up to as much as 

 three-eighths of an inch in height of the 



swellino'. ^^^- ^^- — Section of warble-cell, 



. , °, , -r . T , T . after soaking in water.* 



All that 1 exammed had opemngs on 



the upper side of the hide, and internally were now coated with a 



distinct formation of some kind of lining membrane, like thickened 



yellowish skin, continuous with the coat of the cell below. 



At first the channel down through the hide, and the spot where the 



maggot lies below are merely sores or openings caused by the sharp 



mouth cutters of this then almost microscopic grub. These injuries 



* Figure is repeated from p. 10 to save trouble in reference. 



