PARASITOLOGY. 127 



the plates. These glands empty into the esophagus 

 and the secretion in all probability is a digestive one. 



The neck glands appear as two large spindle-shaped 

 cells located within the perivisceral cavity of the 

 anterior half of the body, and united with the so- 

 called bridge of the excretory system by two longer 

 or shorter peduncles of varying calibre. These glands 

 are provided with excretory ducts which empty on 

 the margin of the buccal lips. It is believed that this 

 secretion has something to do with the prevention of 

 the ready coagulation of the blood ingested by the 

 worm. It has been found by experimentation that 

 these glands secrete a poisonous substance which may 

 interfere with the general health of the infected 

 horse, ass or mule causing an unthrifty condition as 

 well as evidence of injury by a production of an 

 eosinophilia. 



As a rule we may say of the larger species of 

 strongylus, that the Sclerostomum vulgare are found 

 principally in the cecum and at times the colon. The 

 Sclerostomum edentatum and S. equinum are found 

 principally in the first portion of the colon. The 

 Triodontophorus minor is found principally in the 

 thickened end of the terminal portion of the large 

 colon. The triodontophorus serratus and the Cy- 

 lichnostomes are found scattered throughout the 

 cecum and great colon. 



The loss of blood caused by myriads of the blood 

 sucking kind amounts to considerable and yet while 

 nearlv every horse harbors a greater or less number 

 of the various species here described but few ever 

 show any inconvenience. Just to what extent the 



