214 
A. A. SANDOSHAM 
Technique for the Study of Spines 
Particular attention was paid to the cuticular spines since some authorities consider their 
size, shape and arrangement are of great value in species determination. It was found that 
the spines appeared more refractive when cleared in clove oil that when creosote was used. 
Entire mounts were not very satisfactory for the study of cuticular spines. Even when the 
ventral wall was sliced out with a razor and the internal structures were scraped out before 
mounting, the preparation was not altogether satisfactory as it tended to present an oblique 
or an en face view of the spines. The best appearance of the shape and arrangement of the 
spines was obtained by softening the cuticle by leaving overnight in ten per cent caustic soda 
and applying pressure on the coverglass to flatten out the spines. The variations in 
the appearance of spines produced by the different methods of preparing the specimen for 
examination probably account, in some degree, for the confusion and uncertainty on the value 
of spines as diagnostic features in this difficult genus. 
Description (Figs. 2 and 3) 
The body is plump and shaped like a coffee-bean with a flat ventral and a convex dorsal surface. It 
measures about 6 to 7 mm in length and its maximum width, which is near the middle of the body, is 
about 4.5 to 5 mm. 
The oral sucker, which is terminal or sub-terminal in position, is 0.75 mm in diameter. The ventral 
sucker is just in front of the middle of the body in the midline, is rounded and has a diameter of 0.8 to 
0.9 mm. There is a rounded pharynx measuring about 0.2 mm in diameter which leads into a very short 
oesophagus. The latter divides into two broad irregularly wavy intestinal caeca which run along the 
lateral edges of the fluke to its posterior end. 
The cuticular spines are deeply embedded and are best seen on the ventral surface in the interval 
between the two suckers and between the testes. Various workers have shown that for practical diagnostic 
purposes one should concentrate on the more typical spines in these two areas. The spines on the ventral 
surface between the two suckers in this species are not very different from those in the region between the 
two testes. The spines are single and somewhat cylindrical and not much longer than broad. The free 
edge on side view looks rounded with one or two shallow notches. The en face view of the free edge 
appears dimpled in many spines. These singly spaced spines are in closely set irregular rows, the indivi- 
dual spines being about 6 to 20 [ 1 apart. 
The excretory canal from near the posterior extremity in the median plane runs for a distance of 
about 0.6 mm before it dilates into a large pyriform sinus. The latter narrows considerably at about the 
level of the ventral sucker but extends forwards up to the oesophageal region. The details of the terminal 
branches and the flame cell system could not be made out. 
The two testes are now more or less symmetrically arranged towards the dorsal side in the third 
quarter of the body partially overlapped by the vitellaria. The testes are irregularly lobed with finger- 
like processes arising from a central mass. The vasa efferentia run forwards and medially close to the 
dorsal surface and meet to form a seminal vesicle which lies immediately posterior to and slightly to the 
right of the ventral sucker. 
The ovary lies to the left of the median plane in a dorsal position at about the level of the ventral 
sucker. It is a dense lobed structure with one or two of the lobes prolonged into finger-like processes. 
The oviduct is connected to the large yolk reservoir and the ootype is surrounded by the shell gland. 
The uterus, filled with eggs, is a highly coiled organ occupying nearly the entire lateral portion of this 
region to the right of the mid-line. Towards the terminal portion the uterus narrows down to form the 
metraterm which runs medially and opens into the common genital atrium. The genital pore is posterior 
to the ventral sucker in the median plane. 
The operculated yellowish-brown eggs squeezed out of the flukes measure, under a coverglass with 
plenty of water below, 85 to 92 ;j. by 45 to 48JJ.. Each egg is typically oval and symmetrical with the 
maximum width about the middle. The shell has a uniform thickness with a slight general thickening 
at the non-operculated pole. 
The vitelline glands are profusely branched. They are marginal extending the whole length of the 
body and overlapping the gut branches. The median open space is larger on the ventral than on the 
dorsal side. The large transverse vitelline ducts, formed by the fusion of the two longitudinal ducts on 
either side, meet near the midline posterior to the level of the ventral sucker to form a large pear-shaped 
reservoir which opens into the oviduct. 
Discussion 
The identity of the different species of Paragonimus is still an unsettled question. It is 
generally recognised that variations in adult morphology in any single species of Paragonimus 
are too great to be much value in species determination. 
STUD. INST. MED. RES. 
