250 
Larval Flukes from China 
The oral sucker is a powerful muscular organ, some 60/x in diameter. 
Within it there is a small anterior chamber, behind which is a pair of oral 
pockets (Fig. 11), and behind this region a straight narrow lumen which leads 
directly into the small muscular pharynx. This organ is followed in turn by 
a narrow oesophagus, which divides soon to form a pair of pouch-shaped caeca. 
These latter consist of a relatively small number of large glandular epithelial 
cells, with small condensed nuclei and poorly defined division walls, so that 
one is reminded of a syncytium. No ventral sucker has been observed. The 
cephalic glands are confined to the anterior third of the body, outside the caeca. 
They consist of a single granular acidophilous gland (acg) and a group of six 
mucoid basophilous glands {beg) for each side of the body. These glands 
secrete very powerful digestive ferments which are poured out through hollow 
boring spines {cgd) just in front of the oral pockets. 
While this species of furcocercous cercaria cannot be thought of as a mam¬ 
malian parasite, its adaptability for penetration is shown experimentally. 
I placed a few of these larvae in a drop of water on the back of my hand for 15 
minutes and found that they produced a noticeable irritation with the typical 
exanthem of the invasion stage of schistosomiasis. This condition lasted for 
a period of two hours, after which it disappeared. While penetration of the 
skin was not effected, the ability to irritate exposed human skin was demon¬ 
strated. The anlage of the genital organs (ga) is found in a single mass of cells 
just in front of the excretory bladder. The excretory system deserves special 
mention. 
The Excretory System of C. leptoderma. 
In this larva the bladder ( b) lies at the posterior limit of the body on top of 
the proximal end of the tail. It is vesicular, with a pore on the dorsal side some¬ 
what anterior in position. The main collecting tubules of the body arise from 
the anterior side of the bladder and run forward on the outside of the digestive 
CclGCcl. 
Midway in their course they give off the secondary collecting tubules ( ost ). 
After running forward to the anterior region of the caeca they bend mesad 
and fuse on the mid-line with the median collecting tubule {met). This latter 
tubule is itself a fused anterior portion of the inner (anterior) collecting tubules 
of the system. 
The secondary tubules consist of a group of three anterior and three 
posterior units for each side. Each of these runs inward to a cluster of three 
capillaries, each having a flame-cell at its inner end. There are, therefore, three 
anterior groups of three flame-cells and three posterior groups of three flame- 
cells for each side of the body, making 18 flame-cells on each side, or 36 for 
the entire body. The outermost (posteriormost) cluster (/3 in ) is found in the 
tail and performs its function long after the tail is severed from the body. 
Since the pattern consists of an anterior and a posterior portion the formula 
is expressed as (3 + 3 + 3) + (3 + 3 + 3) or «* + a n + a m + jS 1 + 
and the basic formula is a n + /3". 
