340 PARASITES OF ANIMALS 



ficially prepared soil to be still much too moist, I caused further 

 evaporation ; and I afterwards found that the thicker the mud 

 the more suitable it proved as a residence for embryonic nema- 

 todes and earth-worms alike. 



On the 27th I found the small earth-worms in the jar bur- 

 rowing freely and throwing up faecal casts. From one of my 

 watch-glasses the worm had escaped, its place being occupied 

 in the meantime by an actively crawling Julus. I put a second 

 Julus, obtained from the mould in the fern jar, to form a com- 

 panion (in view of other experiments), and I also added a fresh 

 earth-worm, covering all by another inverted watch-glass, which 

 I thought would prevent their escape. 



In the next place I examined the halves of my original 

 experimental earth-worm. They were scarcely capable of 

 motion, but retained a certain amount of vitality. The tail 

 was the more active half, and unfortunately it was soon after- 

 wards lost. Carefully washing the superior half, and transfer- 

 ring its contents to a glass slide, I immediately detected under 

 the microscope a large number of embryos. They were in a 

 state of marked activity, the largest having increased to about 

 35" of an inch in length, whilst their structure had become cor- 

 respondingly advanced. Here, again, there was no room for 

 doubt as to their source, especially as they individually dis- 

 played different degrees of organisation, all answering to one 

 and the same embryonal type. I now observed a distinct 

 oesophagus, the rest of the intestinal tract being still more con- 

 spicuous than heretofore, though, as yet, no true cells marked 

 the limitation of the stomach and chylous intestine. 



After an hour's immersion in cold water some of the larva) 

 became much less active, whilst others were motionless, so that 

 I feared all were about to perish. In the hope of keeping a 

 few of them alive I now added to the slide some finely sifted 

 grains of mould, placing the slide under a small bell jar which 

 protected some of my ferns. The remains of the moribund 

 earth-worm were also covered with mould. 



Other larvae, derived from the earth-worm, were placed on 

 the moist pinnae of a living fern-frond which supported small 

 drops of water, for by this process I hoped in some mea- 

 sure to imitate the dew which naturally condenses on the grass 

 and fodder of our low-lying fields. At 3.15 p.m. of the same 

 day (27th) I also examined a fresh worm pellet from the 

 jar, and found it to contain living strongyle embryos, which as 



