THE ASCARIS LUMBRICOIDES. 99 



nence of the communication between the abscess and 

 the intestines. 



In the third class may be included those cases in 

 which the worm does not reach the purulent abscess 

 until after an external opening has been formed. 



The cases which belong to the j&rst class are rare. 

 It has been attempted to explain them, upon the 

 supposition that the lumbricus traverses the walls of 

 the intestine by the division of the fibres which sub- 

 sequently contract and close the opening through 

 which the worm effected its passage. The absence of 

 foecal matter in the tumour which contains the worm 

 may be explained in another way; a small ulceration 

 may exist in a part of the intestine which is either 

 not invested by peritoneum, or is attached to the 

 abdominal walls by adhesions ; the lumbricus may 

 become entangled in this ulceration, and be conveyed 

 into the neighbouring parts by following an obhque 

 direction, similar to the course of the ureter between 

 the coats of the bladder. It is said that in these 

 cases the patient experiences in the tumour a pecu- 

 liar quivering, pricking, or tingling sensation, and 

 that crepitation may be felt upon a manual examina- 

 tion of the affected part. The symptoms, progress, 

 and treatment of the tumour are similar to those of 

 ordinary abscess. 



The cases belonging to the second class are much 

 more frequent, and have generally an evident con- 

 nection with some primary lesion of the intestine ; 

 they usually occiu in the ingumal or in the umbiHcal 

 region. When the tumour is opened, spontaneously 

 or by a bistoury, a means of exit is given to pus, 

 foecal matter, and worms which may be discharged 



H 2 



