136 ENTOZOA FOUND IN MAN. 



cases which are recorded of hydatid tumours con- 

 taining several cells separated from each other by 

 imperfect septa are not very rare, and these cells 

 may have been produced by the union of several 

 cysts, whose walls have been perforated at the point 

 of contact. 



Hydatids exist principally at the middle period 

 of life, being most common in persons from twenty 

 to forty years of age ; they are almost unknown in 

 young children. 



They do not appear to be of more frequent occur- 

 rence in one sex than in the other. 



It is not conclusively known whether various 

 occupations have any influence upon the frequency of 

 vesicular worms ; it has been remarked by Dr. Budd 

 and Mr. Busk, of the " Dreadnought " hospital-ship, 

 that hydatids are apparently very rare amongst 

 sailors, and it is possible that the diet of seamen, 

 which consists for the most part of salted provisions, 

 may be unfavourable to the development of these 

 entozoa. 



According to Dr. Budd, the poorer classes in 

 England are more often afiected with these worms 

 than the rich are ; and he thinks that this circum- 

 stance may be accounted for by the fact that the poor 

 live in damp, badly-drained houses, and that their 

 diet is less nourishmg and composed chiefly of vege- 

 tables. It is well known that hydatids are very 

 common in sheep and in cattle which graze in marshy 

 pastures, and especially during rainy seasons. The 

 influence of diet upon the production of vesicular 

 worms is therefore tolerably manifest, but its mode of 

 action is as yet almost completely hidden in obscurity. 



