36 ANIMAL PARASITES. 



which the mites breathe is very doubtful, as most of the 

 Arachnida respire through an aperture in the anterior part of the 

 belly. In point of fact, a small, round aperture, surrounded by 

 a horny ring, does exist in the middle of the anterior part of the 

 belly, just behind the end of tke stem which supports the first 

 pair of feet. That this may serve as the opening of the respi- 

 ratory sac is very probable. This supposition acquires still 

 further confirmation from the circumstance that when mites are 

 forcibly pressed, a small air-vesicle collects at this spot, and 

 therefore on the ventral surface of the mite, which can only be 

 got rid of with difficulty. The nervous and circulatory systems 

 are wanting. The animal contains numerous fat- drops. The 

 ovary exhibits one large egg, ripe for laying, of ^" in length and 

 3y"' in breadth, and also several oval eggs of various sizes, of 

 which one female lays more than fifty. They strongly refract 

 the light, lie with their longitudinal diameter in the transverse 

 diameter of the gallery, on the hands in rows of 2 6, on the 

 body in uninterrupted rows of as many as twenty-one close together. 

 The greater number of the eggs in a gallery of this kind are 

 already burst and collapsed at one end. Fresh eggs have 

 amorphous contents, and pass through an ordinary process of 

 segmentation and development up to fully developed young 

 moving in the interior of the shell. In making their escape they 

 extend the bristles, which are at first crossed upon the belly, 

 against the bottom of the shell and burst it. 



The young mite either quits the parent gallery through one of 

 the air holes soon after its exclusion, or eats its way deeper into 

 the bottom of the passage, producing phenomena of reaction, or 

 digs a lateral gallery for itself to the outside, and then burrows 

 in again at a greater or less distance. The mite is now about 

 T ' ? '" in length, and hexapod. 



The male, which is extremely small, lives in small galleries, or, 

 more correctly, in small holes, and appears to die soon after 

 copulation. It is about half the length of the female. The 

 anterior feet resemble those of the female, except that they 

 approach more nearly to the hinder feet than in the latter. The 

 horny frameworks and supports of the individual hinder feet are 

 certainly similar in structure in the two sexes, but in the male 

 they are not free as in the female, but inserted into a slightly 

 sigmoid transverse band, running across the body of the mite, 

 from the central point of which issues an apparatus also of a 



