46 ENTOZOA FOUND IN MAN. 



The ova of the Tricocephalus are expelled with 

 the evacuations, after they have been deposited in the 

 intestine ; but are not developed until some months 

 subsequently. The embryo lives, for a considerable 

 period, enclosed within the shell, and is not hberated 

 until the ovum has re-entered the intestinal canal, 

 through the medium of the food or of the drink. 



The development of the Tricocephalus dispar, and 

 the conditions attendant upon its propagation, closely 

 resemble those of the Ascaris lumbricoides. 



The Tricocephalus dispar exists in the coecum ; 

 less frequently in the colon, or in the small intes- 

 tines. 



Germs Filaria. 



The entozoa included in this genus are of either 

 a white, yellow, or red colour, and of a soft consist- 

 ence ; they are cyhndrical, and filiform in shape, and 

 are very long, the length of the body being from 80 

 to 200 times greater than the breadth ; the body 

 usually tapers off slightly at one of its extremities ; 

 the head is continuous with the body, and is some- 

 times furnished with projecting papillae, or with 

 hom-hke processes, which constitute a protection for 

 it ; the mouth is round or triangular ; the integu- 

 ment of the body is smooth, or minutely striated in 

 the tranverse direction. 



The filariae are found in vertebrated animals, prin- 

 cipally in the mammiferse and in birds, and more 

 rarely in reptiles. 



Three species, or varieties of filaria, have been 

 observed in the human eye. 



