38 Observations on Parasites and Parasitic Diseases 



be taken also to cleanse all sleeping-places and everything con- 

 tiguous to them, where these parasites, either in their perfect 

 form or in one or other of their metamorphoses, are likely to 

 exist. Similar means are to be employed in ridding pigs, and 

 pig-cotes of fleas, and especially should all the old litter be 

 destroyed. 



Pulex penetrans. — The Sand-Flea, Chigger, Chique, 

 Chigue, &c. 



Another of the family of Pulicidce is the Pulex penetrans, a 

 variety from which this country is fortunately exempt. It has 

 been said, however, to exist in the feet of sheep, and to be the 

 means by which "foot-rot" extends in a flock, even in this country. 

 The late Mr. Youatt, who was himself a believer in the contagious- 

 ness of this disease, thus writes : — " Some persons have imagined 

 that foot-rot is propagated by means of animalculae which are bred 

 in the virus of the part, and falling on the pasture attack the feet 

 of other sheep. They have gone so far as to describe this insect, 

 and to give it a name — the Pulex penetrans. The author of this 

 work has often sought for it in vain ; and the sources of con- 

 tagion are numerous, and satisfactory enough without any gra- 

 tuitous supposition of the kind." * 



W ith the question of foot-rot being viewed as a contagious 

 disease we have not now to do ; nevertheless we ought not to 

 allow this opportunity to pass without stating that we are no 

 converts to such a doctrine, knowing full well that the spread of 

 the disorder in a flock depends entirely upon common causes. 



Dr. Stephenson, in his ' Medical Zoology,' thus speaks of the 

 Pulex penetrans : — " One of the most troublesome and noxious 

 insects of the low regions of South America and the West India 

 Islands is the Chegoe, a small species of flea, with a rostrum as 

 long as the body, which often introduces itself into the skin of 

 the inhabitants, usually under the nails of the toes, where it 

 deposits its eggs, and produces malignant and occasionally fatal 

 ulcers. It is a very minute insect, being one-fourth the size of 

 the common flea, pale reddish-brown, semi-transparent or shining, 

 with the legs of a pale blueish or lead colour. According to 

 Ulloa, and his opinion is confirmed by Jussieu, there are two 

 South American species of this insect. It is described as gene- 

 rally attacking the feet and legs ; but, according to Capt. Han- 

 cock, it will penetrate any exposed part of the body. At first 

 it occasions no farther uneasiness than a slight itching and heat ; 

 in process of time, however, a small bladder or membranous 

 sac is formed, containing the nits or ova, which speedily multiply 



* ' Sheep : their Breeds and Management,' p. 534. 



