414 ANIMAL PAEASITES. 



when lie says, u i'osservazione dimostra clic ospitanti ed ospitati 

 vivono in perfetta armonia; gli uni non disturbano il regolare 

 ]>rocedimento dclle favi vitali negli altri •" I nevertheless express 

 the opinion, that, as a general rule, in the case of Ascarides, the 

 host and his guests agree very well together, and give one another 

 very little mutual trouble. Notwithstanding their size, the 

 Ascarides, in themselves, when staying quietly in the intestine, 

 and when they do not occur in too great numbers, bring but 

 little danger to the constitution. Thev probably do not live at 

 all upon ready-formed juices, but, for the most part, upon un- 

 elaborated chyme. A good appetite is almost the whole injury 

 they do, and thus they are much less noxious than, for example, 

 the much smaller Ancylostoma. An abnormal aggregation 

 of Ascarides in the intestine, and a very firm coiling of them 

 amongst themselves into an inextricable knot, may cause mecha- 

 nical obstacles in the interior of the intestinal canal, which 

 may degenerate from simple, temporary stoppage, especially 

 after certain foods, with congestion towards the brain, and 

 all sorts of reflex phenomena caused thereby, to actual ileus. 

 This may be easily understood, when we know cases, for example, 

 in which the body of a child harboured between 300 and 400 

 Ascarides, or in which 103 of these worms were expelled from a 

 child. But in general these phenomena are extremely rare, and, 

 when they do occur, are usually transitory. All kinds of dis- 

 turbances and perversions in alimentation, such as flatulency and 

 tendency to diarrhoeas, are especially produced after certain 

 articles of food, and frequently only occur after offences against 

 proper diet. It is only the worms which have been disturbed in 

 some way, which renders the doctor necessary, whether the dis- 

 turbances are produced by causes in or out of the worms. Internal 

 causes of agitation, that is to say, those which are seated in the 

 worm itself, are perhaps only to be found in the sexual actions. 

 But here we find ourselves upon a field of which we are totally 

 ignorant, as we do not know whether a periodical maturity 

 connected with particular seasons, and a periodical seeking of the 

 females by the males do or do not take place. The smallest 

 Ascaris which I have seen, and which I still preserve as a micro- 

 scopic preparation in my collection, I expelled from myself, at the 

 end of July. It is the sexually immature worm already men- 

 tioned, of about \\ inch long. We must therefore quit this 

 subject, by openly confessing that the causes of excitement to 



