DIRECT INJURIES CAUSED BY INSECTS. 85 



regard me as guilty of presumption, and of intruding 

 mto the province of medical men, if I enter rather largely 

 into it, and state to you the reasons that have induced 

 me to embrace the above hypothesis, leaving you full li- 

 berty to reject it if you do not find it consonant to reason 

 and fact. The three kinds of insects to which I allude, 

 as concerned in cases that have been deemed Phthiriasis, 

 are lice (Pediculi, L.), mites (Acari, L.), and Larvce in 

 general. 



As far as the habits of the genus Pedzculus, whether 

 inhabiting man or the inferior animals, are at present 

 known, it does not appear, from any well ascertained fact, 

 that the species belonging to it are ever subcutaneous. 

 For this observation, as far as it relates to man, I can 

 produce the highest medical authority. " The louse feeds 

 on the surface of the skin," says the learned Dr. Mead 

 in his Medica Sacra ; and Dr. Willan, in his palmary 

 work on Cutaneous Diseases, remarks with respect to the 

 body-louse, " that the nits, or eggs, are deposited on the 

 small hairs of the skin," and that " the animals are found 

 on the skin, or on the linen, and not under the cuticle, 

 as some authors have represented." And he further ob- 

 serves, that " many marvellous stories are related by Fo- 

 restus, Schenkius and others respecting lice bred under 

 the skin, and discharged in swarms from abscesses, stru- 

 mous ulcers, and vesications. The mode in which Pe- 

 diculi are generated being now so well ascertained, no 

 credit can be given to these accounts." Thus far this 

 great man, who however supposes (in which opinion Dr. 

 Bateman concurs with him) that the authors to whom he 

 alludes had mistaken for lice some other species of insects, 

 which are not unfrequently found in putrefactive sores. 



