WOUMJS. 207 



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

 one 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 and can be withdrawn into the body.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. 



Fu;. 1!H. — Le/iloilr, 



xopItUa, vinegar 



Class IV. — ^EMATODA. 



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

 is Leptodera oxophila, but most authors still call them Aiit/uiUida 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 I^eptoderu has a poor 

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

 the vinegar, but on the fungi which grow in it, 

 and which depend on the sugar for nutriment. If 



any one wishes to observe these mici-oscojiic worms, it is oidy necessary to add a little 

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

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

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

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

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

 name, L. fjlutinis. 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, 

 transpai-ent, and has a digestive canal which occu])ies neai'ly the whole length of its 

 body. At the anterior end is the long, muscular oesoi>hagus ; 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 wi'iggle 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 shape. Indeed, despite the great number of 

 species, they present a remarkable uniformit}', 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 Lep>todera 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 Leptodera and the allied Peloderu live in moist earth and 

 [lutrefying 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 

 keej) 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 sjiot to 



