62 



THE EMBRYO IN THE EARTHWORM. 

 The embryo as found in the earthworm differs but slightly in 

 its structure, so far as can be discovered, from the embryo 

 which has passed througli one moult after the egg has hatched in 

 water. We think the granular material extends throughout the 

 whole length of the body, instead of only its posterior half, as 

 when hatched in water. It is also a little larger, about .0118 inch 

 long, and has a diameter of about .00078 inch at the middle of its 

 body. They differ somewhat in their size, which probably de- 

 pends on how long they have been in the earthworm, and I think 

 those residing in very large earthworms are larger than those liv- 

 ing in smaller ones. The method of finding them in the earth- 

 worm is as follows: Select a poultry yard where chicks have had 

 the gapes for several years, so that the earthworms may have plen- 

 ty of the parasites. From near the surface of bare spots of 

 ground which chicks with the gapes have frequented, take some 

 of the earthworms and examine them wath the microscope. The 

 following method is recommended: Throw the earthworm to be 

 examined into a solution of common salt (Chloride of Sodium), 

 having the strength of about two ounces to the pint of water. 

 When it ceases to move rinse in pure w^ater ; then, with sharp- 

 pointed scissors slit the skin the entire length of the worm down 

 the back. Spread out on each side, to expose the digestive or- 

 gans. In order to intelligently proceed, we will briefly describe 

 these: They consist of the mouth, pharynx, oesophagus, crop, 

 gizzard and intestine. Directly connected with the oesophagus, 

 about its middle and posterior part, are found six white bodies, 

 three on each side, called the oesophageal or calciferous glands. 

 The oesophagus passes directly into the crop, which is just in 

 front of the gizzard. Following this is the intestine, which 

 passes through the remaining portion of the worm. We cut off 

 the intestine just back of the gizzard, and taking small pieces, 

 about one-eighth inch long, place them on a watch glass with a 

 little water, pick them well in pieces, and examine carefully 

 with an inch objective. We generally find the embryos a short 

 distance below the gizzard, not often more than half way to the 



