63 



tail. There are numerous kinds of parasites which inhabit the 

 earthworm, some of them numbering thousands in a single 

 worm. We have also found the earthworms in different locali- 

 ties to harbor very different kinds of parasites. The method of 

 distinguishing the embryo of Syngamus is its size, description 

 as here given, and general appearance as seen in the engravings. 

 We think it is taken in by the earthworm with its food, and 

 passes down into the intestine, where it remains until trans- 

 ferred within its host to the digestive organs of some bird, or 

 after a time passes through into the soil and perishes. We be- 

 lieve this method of taking in the embryo by the earthworm is 

 the common law in nature, through which all creatures, man in- 

 cluded, obtain their intestinal parasites. 



THE EMBRYO OF SYNGAMUS IN THE FOWL. 



The embryo passes into the crop within the intestine of the 

 earthworm. We wish to determine at what point it leaves 

 the digestive canal and passes into the lungs and trachea. We 

 have never been able to trace the embryo below the oesophagus, 

 after many examinations of chicks dead of the gapes If we 

 admit that they do not pass through the proventriculus and giz- 

 zard alive, which I have no doubt is the truth, there are only 

 two organs, the crop and oesophagus, through which they could 

 gain admission to the lungs. The crop is simply a dilatation of 

 the oesophageal structures, and acts as a reservoir for the food. 

 We believe the embryo passes through the oesophagus just above 

 the proventriculus, for the following reasons: The distance to 

 the lung structures is very short, only the thin wall of the oeso- 

 phagus intervening. The orifices of the lenticular glands of the 

 oesophagus are of greater diameter than the embryo, so it could 

 readily enter through them. That such is the case we know, for 

 we have found them beneath its mucous membrane. The pul- 

 monary bronchi ramify over the outer surface of the oesophagus, 

 through the substance of which there are numerous tubular 

 structures, which, it is not improbable, may be connected with 



these. We have seen the embryo just emerging from the ceso- 



2 



