338 PARASITES OF ANIMALS 



nematoid larvae can resist the fatal action of putrid matter, 

 however slight the putrescence. 



Having removed the offending shreds, I next placed a quan- 

 tity of living ova together in the earthenware jar, and allowed 

 the earth-contents to become much drier by evaporation before 

 the fire. I also left others in a watch-glass, which was placed 

 under a bell-jar enclosing several ferns. 



On the 25th of October I removed particles of the moist earth, 

 altogether weighing about two grains, and, on submitting them 

 to microscopic examination, had the satisfaction to observe about 

 a dozen living embryos, some of which exhibited very lively 

 movements. There was not the slightest indication of putridity ; 

 nevertheless, I noticed several shreds of the adult worms whose 

 presence had been accidentally overlooked, and, curiously enough, 

 all the embryos subsequently removed from the immediate 

 neighbourhood of these decomposing shreds of tissue were 

 almost motionless and apparently in a moribund condition. 

 On examining the contents of the watch-glass placed under the 

 fern shade, I noticed several points of interest. First of all 

 the earth contained strongyle embryos, such as I had seen 

 before. Secondly, the surface of the mould was being traversed 

 by three or four briskly- moving Thysanurida, hunting about 

 with all that restless activity which Sir John Lubbock has so 

 welL described. Thirdly, in marked contrast to the behaviour 

 of these I noticed several slow-moving Acarida, apparently also 

 employed in searching for food. And lastly, while thus engaged, 

 the surface of the mould in the centre of the deep watch-glass 

 was suddenly upheaved, by which I was at once made aware of 

 the presence of another most welcome and unexpected intruder. 

 In short, an earth-worm had crept from the dry mould in which 

 the ferns were growing, and had taken up its temporary abode in 

 the soft moist experimental-earth contained in the watch-glass. 

 When contracted, this Lumbricus terrestris was barely an inch 

 in length. On placing it under the half-inch objective glass, I 

 noticed a single embryonic strongyle adhering to the skin, but 

 not firmly, and evidently only in an accidental way, so to speak. 

 It was clear to me that it possessed neither the intention nor the 

 power to penetrate the chitinous integument of the earth-worm. 



Having in the next place removed the Lumbricus with a pair 

 of forceps, and having washed it under a current of water, I 

 snipped off the lower end of the body, and allowed some of the 

 intestinal contents to escape on a clean glass slide for separate 



