6 On a Variety of the Genus AcaruS. 



pear like fine gauze. The whole fly about the size of the 

 common gnat. 



Upon a minute examination of the plumage, Sec. I ca- 

 sually discovered the subject of this paper : whereupon I 

 took a deeper magnifier, which enabled me to see that every 

 part abounded with them, and that the one I first saw was 

 not an accidental visitor, but that they were the common 

 vermin with which this fly is infested ; which indeed is 

 no great wonder, when it is considered that far less creatures 

 have some peculiar tormentor; for even that notably dis- 

 gusting pestilence the louse is not exempt, but is over-run 

 at times with his pediculi, in return for the compliments he 

 pays to some of us *. 



The object of my pursuit was now diverted from the fly 

 and his plumage to his incumbent tormentors, which I soon 

 discovered to be of the oviparous kind, and that some hun- 

 dreds of the ova were scattered oVcT one wing, several of 

 \\ hich I saw drop off" the parents while they perambulated 

 their prey, which were afterwards nidified, or hatched. 



I should have observed before, that the eggs of this insect 

 are never incubated at all, but instead thereof the parent 

 literally clothes herself with them ; for by means of some 

 kind of mucilage, which either exudes from the parent, or 

 with which the ova are covered, they firmly adhere to her : 

 but it is most natural to suppose this supply is from tha 

 parent, by which means the ova arc brought to perfection ; 

 and as this nuicus is absorbed they harden and fall ofl'; after 

 which, in a few days, a development takes place. And here 

 the agency of the sun is of •essential service, as it not only 

 very much accelerates their maturity, but also stimulates the 

 full grown to fulfil the great purpose of nature, which they, 

 like the canine breed, perform posteriorwisc. But I never 

 saw the least propensity to this act until they were placed 

 in that situation, or any of the eggs hatched anterior to 

 this: but all their motions were slow and languid heretofore ;- 

 whereas now they became reanimated, with the greatest 

 promptitude imaginable, running about with amazing cele- 

 rity, bcc. Tlie rotundity and semi-transparency of their 

 bodies gave them the appearance of moving prolate sphe- 

 roids of moistened ichthyocolla, and quite as clear through- 

 out ; for, like all insects, their blood is as limpid as distilled 

 water, so that there is no impediment to the sight. And 

 'as the microscope I applied them to magnified several thou- 



* Thus a distinct species of pulen, gorged with a serrated collar, is found 

 tin the mouse : — aiid all creatures liave some kiud of vermiii. 



sand 



