86 JOURNAL OF THE 



a dark line reaching to near tlie swelled portion of the cyst 

 where is the middle part of the oesophagus. The middle part 

 of the oesophagus is an ovoid or ellipsoidal transparent muscular 

 bulb, which has a fibrillate structure, the fibrill?e radiating from 

 the centre. Seen in side view this bulb looks very much like a 

 small wheel. In Plate VI, Fig. 34, 6, is the bulb or middle part 

 of the cesophagus. The slender, tortuous channel, forming the 

 anterior part, is represented connecting this with the base of the 

 spear a. The posterior part of the oesophagus connects with 

 the alimentary canal, neither of which are represented in the 

 figure, as the mass of fat globules usually renders the body too 

 opaque at this age. 



Were it not for a slight movement of the ap})aratus just 

 described, or a trifle ''nodding'^ of the head, there would be 

 nothing to suggest what we ordinarily consider a sign of life. 

 Occasionally, even while the cyst is under microscopic examina- 

 tion, the exsertile spear is thrust slowdy out at the mouth and 

 then drawn back ; at the same time the anterior part of the oesoph- 

 agus, being connected with it, is also moved. Sometimes the 

 apparatus slides far enougii so that the tortuous anterior part of 

 the <jesoj)hagus is straightened and the bulb is moved a little for- 

 ward and backward. Sometimes there appears also a slight side- 

 wise movement of the anterior part of the head, a sudden 

 ''jerky" motion. This sidewise movement of the head is 

 probably from force of the habit of the worm in its larval stage 

 when movement from place to place is accomplished by a con- 

 stantly changing tortuous motion of the body. Miiller* speaks 

 of an ex[)ansion and contraction of the middle part of the oesoph- 

 agus which he has observed. By this means nutriment from 

 the plant is sucked in through the lumen of the spear into the 

 oesophagus and thence into the alimentary canal. Now turning 

 the eye upon the large part of the body the first thing to attract 

 attention is the presence of two long (cylindrical objects coiled 

 within. Usually at this age of the cyst the develo})ment of 



*Mittheilungen uber unseren Kulturpflanzen seliadliche, das Geschlecht Heterodera 

 bildenden Wurmer, 1884. 



