754 



A HISTORY OF 



same time, to make room for this new sup- 

 ply- 



The louse has neither bersk, teeth, norany 

 kind of mouth, as Dr. Hooke described it, for 

 the entrance into the gullet is absolutely 

 closed. In the place of all these, it has a 

 proboscis or trunk ; or, as it imy be other- 

 wise called, a pointed, hollow sucker, with 

 which it pierces the skin, and sucks the hu- 

 man blood, taking that for food only. The 

 stomach is lodged partly in the breast and 

 back; but the greatest portion of it is in the 

 abdomen. When swollen with blood, it ap- 

 pears of a dark brown colour, which is visi- 

 ble through the skin; and is either a faint 

 red, or a full or bright brown, as the contents 

 of the stomach are more or less changed. 

 When it is empty, it is colourless; but when 

 filled, it is plainly discernible, and its motion 

 seems very extraordinary. It then appears 

 working with verystrongagitalions,and some- 

 what resembles an animal within an animal. 

 Superficial observers are apt to take this for 

 the pulsation of the heart ; but if the animal 

 be observed when it is sucking, it will thru 

 be found that the food takes a direct passage 

 from the trunk to the stomach, where the re- 

 mainder of the old aliment \\ill be seen mix- 

 ing with the new, and agitated up and down 

 on every side. 



If this animal be kept from food two or 

 three days, and then placed on the back of 

 the hand, or any soft part of the body, it will 

 immediately seek for food ; which it will the 

 more readily find, if the hand be rubbed till 

 it grows red. The animal then turns its head, 

 which lies between the t\vo fore legs, to the 

 skin, and diligently searches for some pore : 

 when found, it fixes the trunk therein ; and 

 soon the microscope discovers the blood as- 

 cending through the head, in a very rapid, 

 and even frightful stream. The lonse has at 

 that time sufficient appetite to feed in a;iv 

 posture ; it is then seen sucking with its head 

 downward, and its tail elevated. If, during 

 this operation, the skin be drawn tight, (he 

 trunk is bound fist, arid the animal is incapa- 

 ble of disengaging itself; but it more fre- 

 quently suffers from its gluttony, since it gor- 

 ges to such a degree, that it is crushed to 

 pieces by the slightest impression. 



Whether lice are distinguished by the parts 



of generation into males and females is not 

 yet discovered : Swammerdana is inclined to 

 think that they are hermaphrodites. 1 avhg 

 foutid an ovary in all those he exrnined; 

 and he dissected not less than Ibrly-two. In 

 one of these animals were found ten large 

 eggs; and forly-tbur smaller, (hat were not 

 yet come to their full perfection. 



There is scarce any animal that multiplies 

 so fast as this unwelcome intruder. It has 

 been pleasantly said, that a louse becomes a 

 grandfather in the space of twenty-lour hours; 

 this fact cannot be ascertained : but nothing 

 is more true than the moment the nit, which 

 is no other than the egg of the louse, gets rid 

 of its superfluous moisture, and throws ofTits 

 shell, but it then begins to breed in its turn. 

 Nothing so much prevents the increase of this 

 nauseous animal as cold and want of humidity; 

 the nits must be laid in a place that is warm, 

 and moderately moist, to produce any thing. 

 This is the reason that many nits laid on the 

 hairs in the night-time, are destroyed by the 

 cold of the succeeding day; and so stick for 

 several months, till they at last come to lose 

 even their external form. 



The louse is found upon every part of the 

 human body; but particularly in the heads 

 of children. Those found upon the miners 

 in Sweden, are said by Linna?us to be very 

 large ; and he is of opinion that the head and 

 the body-louse differ in no respect from each 

 other. The pthiriasis,or lousy disease, though 

 very little known at present, was frequent 

 enough among the ancients: Herod, Airii- 

 ochiis. Epiphanes. Alcman. the poet, Pherecjv 

 des. Cassander, Callisthenes, and Sylln. all 

 died of this disorder. The use of mercury, 

 which was unknown among the ancients, may 

 probably have banished it from among the 

 moderns ; for certain it is, that these animals 

 seldom attack any in our climate, but such 

 as fro'n slo'h or famine invite their company. 



Such is the history of the human louse, 

 which, from its connection with mankind, de- 

 serves first notice : but it would be endless 

 to describe the various tribes that go under 

 this name, and swarm upon every part of na- 

 ture. There is scarce an animal, and scarce 

 even a vegetable, that does not suffer under 

 its own peculiar louse. The sheep, the 

 horse, the hog, and the elephant, are all 



