STEM EELWORM. 



53 



irregularly, and oval- (or somewhat bulb-) shaped ; but some- 

 times they were much prolonged, so as to resemble what is 

 known as a "duck-necked" Onion in shape, and sometimes 

 the lower part of the flowering stem was enlarged for an inch 

 or two at the base. 



In some instances the short, brown, deformed shoots had a 

 little bit of deformed shoot or of leaf -growth proceeding from 

 it. One of the shoots, which was merely swollen, not al- 

 together shortened by disease, on being opened, proved hollow 

 near the base, with decayed matter within, and also palish 

 brown powdery or rather damp granular matter, and on 

 placing this under a one-inch object-glass it proved to be 

 swarming with Anguillulidce, or "Eelworms." _ Under a 

 quarter-inch object-glass I clearly distinguished in some of 

 these the presence of a mouth-spear with a bulbous base.J 



These specimens were examined for me by Dr. Eitzema 

 Bos, and by Dr. J. G. de Man, of Middleburg, likewise a well- 

 known expert in the difficult study of these minute but very 

 injurious wormlets, and were pronounced to be certainly cases 

 of Clover Stem-sickness caused by the Tylenchus dcvastatrix 

 found within. During the investigation of the last few years 

 this special infestation has been found to be one of our regular 

 attacks, but I give the preceding notes in detail to describe 

 the precise appearance of an attacked crop. 



It is not at all unusual to find various kinds of Eel worms 

 feeding in the withering or decay- r^ 



ing parts of plants suffering from 

 Tylenchus attack, although these 

 other species, as far as observa- 

 tions go at present, never cause 

 the Clover " Stem-sickness." 



One main point of distinction 

 of these Nematodes, or "thread- Kfv 

 worms," is the form of the oeso- 

 pJiagus, or gullet, by which food 

 is sucked into the wormlet. In 

 some cases the mouth-cavity is 

 furnished with a long process, 

 called a spear, and in the Ty- 

 lenchi this spear is placed on a 

 trilobed bulbous base. The ac- 

 companying figure gives some 

 idea of a few of the forms of the 

 mouth-extremity of different kinds 

 of Nematodes.* 



* For details of the history of the Tylenchus devastatrix, together with 

 excellent plates, see ' L'Anguillule cle la Tige, Tylenchus devastatrix par 



^: 



:a 



AnguillulidiB : 1, Tylenchus oh- 

 tusus; 2, Aphelenchus aveme ; 3, 

 Plectus granulosus, real size micro- 

 scopic. Fromfigs.byDr. C.Bastian. 



