WORMS. 207 



as well as the bristles and red eye-specks on the head, and also the caudal fork, reminds 

 ope strongly of the Gastrotricha. A false appearance of segmentation or jointing of 

 the body is produced by ten rings of spines. The head is quite distinctly marked off, 

 and can be withdrawn into the body. The sexes are said to be distinct. 



Class IV. — NEMATODA. 



The well-known " vinegar eels " are typical JSTematods. The true name of vinegar eel 

 is Zeptodera oxopMla, but most authors still call them Anguillula aceti. The older 

 writers describe them as very abundant in vinegar, 

 but nowadays they are not so common. Formerly 

 vinegar was prepared so that a good deal of sugar 

 was left in solution, but at present the processes of 

 manufacture used eliminate nearly all the sugar, 

 and, morever, the vinegar is too often adulterated 

 with sulphuric acid, so the Zeptodera has a poor 

 chance.' The vinegar eels, however, do not live on 



the vinegar, but on the fungi which gl'OW in it, ^^'^- ^^^- ~ Leptodera oxophUa, vinegar 



and which depend on the sugar for nutriment. If 



any one wishes to observe these microscopic worms, it is only necessary to add a little 

 sugar and mucilage to some vinegar and allow the mixture to stand in an open dish 

 for a few days. A fungous growth appears, in which the eels develop, and they may 

 be seen readily by scooping up some of the fungous mass, spreading it upon a glass 

 slide, and examining it under the microscope. The same worm, apparently, appears 

 in fermenting starch paste, although the paste worm has received a different specific 

 name, Z. glutinis. The worm never exceeds a couple of millimetres in length ; in 

 English measure it is always less than the twelfth of an inch. It is long, cylindrical, 

 transparent, and has a digestive canal which occupies nearly the whole length of its 

 body. At the anterior end is the long, muscular oesophagus ; in the middle lie the 

 elongated reproductive organs, alongside the intestines. In the female the eggs are 

 quite conspicuous, shining through the body wall. The external surface of the body 

 has a tough crust, yet a very elastic one, else the animal could not wriggle and twist 

 as it does. Now all theSe features are common to the nematods in general, and they 

 owe their very name to their thread-like shajje. Indeed, desjaite the great number of 

 species, they present a i-emarkable uniformity, not only in appearance, but also in organ- 

 ization. The most noticeable variations are in the outline of the body, the armature 

 of the mouth, and the form of the caudal extremity. Now in all three of these 

 respects the Zeptodera is as simple as possible ; the mouth is a simple opening, the 

 body a simi>le cylinder, and the tail simply tapers off. It is organized like one of 

 Mother Goose's repetitive melodies. 



Nearly all the species of Zeptodera and the allied Pelodera live in moist earth and 

 putrefying substances. Our knowledge of their curious habits is mainly due to the 

 experiments of Anton Schneider, whose account we reproduce in abstract. To obtain 

 the species it is only necessary to have a pot with some earth in it, it matters little of 

 what soil ; put a small piece of meat or pour a little blood or milk into the earth, and 

 keep it moist, not wet. The earth contains great numbers of the larvae, which attracted, 

 perhaps, by the smell, crawl to the centre of putrefaction, where they soon swarm. 

 They become sexually mature, and the young they produce develop on the spot to 



