ON PARASITES. 27 



Tentral cavity is triangular. The male is smaller than the female. 

 The caudal extremity somewhat curved and involuted. 



The much convoluted testis terminates at the tail in a retractile 

 penis. 



The female is larger than the male. The tail is straighter and 

 longer. The vagina is simple and is situated anteriorly to the middle 

 of the ventral surface. The uterus is single and large, the ovarian 

 apparatus douhle, extensive and convoluted. The variety found in 

 man infests the small intestines. 



The Filaria Medinensis as it is found in the suhcutaneous cellular 

 tissue of the human subject is about as thick as a crow's quill, several 

 feet in length, white in color and commonly single, although there 

 may be several worms at the same time in different parts of the body. 

 In tropical regions of the East it infests both natives and Europeans, 

 although the latter much more rarely. It has the ordinary character- 

 istics of a Filaria. A round elastic elongated body, a terminal 

 orbicular mouth. The body continuous with the head, the oesophagus 

 is short and tolerably straight. The anus terminal or anterior to the 

 caudal extremity. The skin is striated. The males of this Filaria are 

 not known. The vagina in the female is anterior, near the mouthy 

 double, as is the uterus. It is viviparous. 



The common tank worm of the East is probably the Filaria M. in an 

 earlier stage of existence. This tank worm, brought into contact by 

 whatever means with the naked skin, insinuates itself into a cutaneous 

 follicle, which it may well do from its small size, and boring its way into 

 the subcutaneous cellular tissues, in time becomes the Filaria. The 

 origin of the tank worm is unknown. It is a significant fact that 

 whilst the pus from the abscess formed by the Filaria often abounds in 

 small so-called Filariae ; they never develope themselves into animals 

 like the parent. This would seem to indicate that the so-called vivi- 

 parous female is a mere sporocyst, like that of the Distoma. 



The Ancyclostoma Duodenale occurs along the river Nile in vast 

 numbers ; it is quite small, but provided with a most effectual oval 

 apparatus for fastening upon the intestinal mucous membrane, whose 

 small bloodvessels it often cuts across and thereby causes hsemorrhage 

 that is not unfrequently fatal. It subsists upon blood — at least that 

 fluid is to be seen in it. The prominent symptoms that result from its 

 attacks are those of anaemia with intestinal irritation. 



