F. H. Stewart 
169 
VI. A. OLESISTUS R.B. 1893. ANATOMY. (Figs. 21, 23, 24.) 
Measurements. $ L. 0-529 mm., B. 0-011 mm., a 48, (/3 8), y 20. $ L. 0-574 mm., a 44, 
(/3 11), y 19. L. 0-5 mm., « 50, (/3 8-87), y 15. 
Cobb’s formula: 
1-8 (9) 11-8 ? 70 95 
( 1 - 8 ) 
? 2-3 1-2 
0-574. 
In general anatomy, this species, as well as A. fragariae, so strongly resembles A. 
phyllophagus, that it is necessary to refer to a few points only. Cuticular striae are not 
visible. Spear, 0-01 mm. Excretory system, the renette cell ( R) lies in the same position on 
the left side; the excretory pore (E) is however at the level of the nerve ring. Reproductive 
system: female, the structure is naturally more difficult to distinguish than in the larger 
species; in the specimen figured the uterus is occupied by a large cylindrical egg without 
a shell; the sphincter at the junction of uterus and anterior vagina is well developed; the 
spermatozoa occupying the anterior vagina are arranged in a rouleau. (The posterior 
vagina extends further back than is shown in Fig. 21, to the point marked VPX.) 
Male spicules (Fig. 24). Length, 0-013 mm.; no accessory piece, no caudal papilla. 
VII. A. FRAGARIAE R.B. 1891. ANATOMY. (Figs. 22 and 25-29.) 
Measurements. $ L. 0-723 mm., B. 0-012 mm., head to posterior margin of bulb, 0-065 
mm.; tail, 0-038 mm., a 60, (/3 11), y 19. 
Cobb’s formula: 
1-6 (9) 11 ? 69 93 
0-8 ( 1 ) 1*1 ? 1-6 1 
0-723. 
This is the most slim of the three species, especially as regards the oesophageal region 
of the body. Compare breadth at the nerve ring, 1-1 per cent, with 2 per cent, in A. 
olesistus. 
Spear, 0-01 mm. Oesophageal bulb conoid to cylindrical (Figs. 25, 26). Rectum (Fig. 27), 
long, nearly equal to the length of the tail. The anterior lip of the anus is prominent (Figs. 
27, 28). Excretory pore at the level of the anterior margin of the nerve ring. Female repro¬ 
ductive system: the uterus is well-defined (Fig. 22, U), and is marked off from the anterior 
vagina by the sphincter (SPH); the anterior and posterior vaginae are of equal length. 
Spicules of the male (Fig. 29), 0-014 mm.; no accessory piece, the accessory of Ritzema Bos 
being again the anterior margin of the spicule. 
VIII. COMPARATIVE ANATOMY OF (1) THE OESOPHAGUS AND SALIVARY 
GLANDS, (2) THE RENETTE, (3) THE VAGINAE, IN THE ■ 
GENUS APHELENCHUS. 
1. The Oesophagus and Salivary Glands. In this genus the oesophagus 
is usually described as terminating at the bulb, and as joining the intestine 
at that point. The following facts, however, prove that the section of the ali¬ 
mentary canal between the bulb and the point of commencement of the 
intestinal droplets and granules (Figs. 1, 16-19, 21 and 22, 01) is morphologic¬ 
ally the posterior oesophagus: (1) it is embraced by the nerve ring; (2) it is 
Fig. 21. A. olesistus R.B., adult female from cabbage seedling infected 14 days previously from 
Lomaria, ciliata. Fixed in Bouin’s sol., mounted in glycerine jelly. (Note: The posterior 
vagina extends to the point VPX.) 
Fig. 22. A. fragariae R.B., adult female from bud of ; rawberry plant; fixed in Bouin’s sol., 
stained with haemalum, and mounted in balsam. 
