F. H. Stewart 
171 
clothed by the oesophageal cellular collar; (3) its walls are eosinophil in con¬ 
trast to the basophil intestine; (4) its lumen is cylindrical, that of the intestine 
is flattened. The lack of a definite line of demarcation from the intestine is 
due to the separation of the oesophageal glands from the body of this portion 
of the oesophagus, which will be considered in the next paragraph. 
The salivary glands have been described in Tylenchus similis Cobb, by 
that writer (1915). They resemble those of Aphelenchus phyllophagus, olesistus, 
and fragariae. (Cobb has, however, traced their duct through the substance 
of the bulb and anterior oesophagus to an opening at the base of the spear.) 
The posterior oesophagus in Tylenchus similis also resembles that of the 
Aphelenchi, and differs from the corresponding organ of other Tylenchi, e.g. 
T. dipsaci Kiihn, in which it is thick, club-shaped, and glandular, and is 
sharply marked off from the intestine (Fig. 30). In T. dipsaci this posterior 
bulb contains several large nuclei in its dorsal wall, while no salivary glands 
are present. It is therefore a reasonable supposition that the posterior oesopha¬ 
geal bulb of the Tylenchi (less T. similis) represents, morphologically and 
physiologically, the combined posterior oesophagus and salivary glands of 
Aphelenchus and T. similis ; in other words, the oesophageal glands of Tylem 
chus, which are situated in the dorsal sector of the posterior bulb, have, in 
Aphelenchus and T. similis, separated themselves from the oesophagus to 
form the salivary glands. 
Considering further the anatomy of the oesophagus and its glands, in 
other nematode genera, we find three glands, one in each longitudinal sector 
of the organ, which open by three ducts into the alimentary canal ( Thora - 
costoma and Cylicolaimus Jagerskiold, 1901; Oncholaimus Stewart, 1906; 
Ascaris, adult, Jagerskiold; Agchylostoma Looss, 1911). The dorsal gland 
is, however, always more important than the two subventrals, is longer, and 
stains more deeply (Jagerskiold, 1901, p. 14). Finally on examining the larva 
of Ascaris lumbricoides (Stewart, 1921), we find that these three glands ori¬ 
ginate from a single giant nucleus in the hind end of the dorsal sector, which, 
as growth proceeds, expands downward into the sub ventral sectors. We 
therefore have in series (1) Aphelenchus and T. similis with the glands separate 
from the oesophagus, on its dorsal surface, as the “salivary glands'’; (2) Ty¬ 
lenchus (less T. similis) and the larvae of Ascaris to the seventeenth day, with 
Figs. 23, 24. A. olesistus R.B. 
Fig. 23. Male, outline of oesophageal region. 
Fig. 24. Male, spicule. 
Figs. 25-30. A. fragariae R.B. 
Fig. 25. Male, outline of oesophageal region. 
Fig. 26. Female, outline of tail. 
Fig. 27. Female, outline of tail. 
Fig. 28. Female, outline of oesophageal region. 
Fig. 29. Male, outline of tail. 
Fig. 30. Tylenchus dipsaci (devastatrix) Kiihn, from clover, fixed in 70 per cent, alcohol’, 
mounted in glycerine jelly. 
