Parasitic Worms 
390 
and found that they penetrated the stomach or intestinal wall, thus reaching 
the peritoneal cavity, whence by penetrating the diaphragm and pleurae they 
reached the lungs. According to Yoshida, therefore, the worms, unlike Bil- 
harzia , reach their ultimate destination, the lungs, by their own migratory 
efforts, without the aid of the blood vascular system. He does not entirely 
account for the occasional occurrence of the worms in the brain though he 
states that “some of the worms may proceed cephalad, taking their course 
through the loose connective tissue along the oesophagus or the blood vessels.” 
Later experimental work of Yokogawa and Suyemori (1921) on intracranial 
infection has failed to solve this point so that for the present we must accept 
Yoshida’s supposition as a working hypothesis. 
We have now dealt with what are generally considered (from a pathogenic 
and public health point of view) to be the most important parasitic worms. 
There remain, however, several others to which at least passing reference 
must be made. Of these Trichuris trichiurus (Trichocephalus dispar) has prob¬ 
ably attracted most attention. It is a worm which in itself is possibly of 
second-rate pathogenic importance but which as a predisposing agent in 
serious intestinal affections may play a more definite part than has been 
generally believed to be the case. There appears to be quite strong evidence 
to associate it with a form of enteritis (Garin, 1912) and it is certainly suspect 
as a predisposing factor in cholera (Guerrini, 1915), and dysentery (Brau, 
1914). An extensive monograph on the worm has been written by Christoffersen 
There appears some ground for supposing that Trichuris like Ascaris and 
Ancylostoma pursues a complicated route of invasion in its host, but the only 
evidence so far reported is that of Neshi (1918) who recorded the finding of a 
few larvae of T. depressiusculus (the whipworm of the dog) in the lungs within 
twenty-four hours after the ingestion of Trichuris eggs. 
Also, according to the observation and opinion of Yokogawa (1921), 
another allied worm, Trichosornoides crassicauda , the common parasite of the 
urinary bladder of rats, has a similar migratory course via the lungs, but the 
route of the larvae from the lungs to the bladder has not been traced. T oko- 
gawa, however, considers that von Linstow s observation in 1874 of young 
worms in the kidneys and ureters is suggestive that the worms enter the bladder 
by way of the kidneys. Further investigation, however, is necessary to com- j 
plete our knowledge of the migratory course in the case of this parasite. Its 
importance as a pathogenic agent is evidenced by the fact that it may giv e rise 1 
to papillomatous growths in the bladder and apparently also in the kidneys • 
(Lowenstein, 1912). < 
Allied to Trichuris but of much greater economic importance is the measle 
worm ( Trichinella spiralis). Its frequency and dangerous nature are notorious 
in many parts of Europe. A comprehensive account of the structure and 
pathogenicity of this parasite is given by Staubli (1913), but further researches 
on the toxic properties of the worm have been made by Flurv (1913). 
