146 Parasitic Worms 
the new method is not less cumbrous than the old one and is hardly so 
exact. 
On the Cestodes the most interesting work, perhaps, is that by Cohn 
(1906 and 1911), Kofoid and Watson (1910) and Watson (1911) on the 
orientation of the Cestode strobila. From the detailed study of the 
nervous system these authors come to the conclusion that the scolex or 
so-called head of a tape-worm is really the posterior end. Valuable work 
has also been done by Gough (1911) on a group of Cestodes which he 
has formed into a sub-family Avitellininae, characterised by the absence 
of yolk-glands. Interesting work on the histogenesis and cytology of 
the Cestodes has been accomplished by Young (1910) and Richards 
(1911). 
With regard to Nematodes the most remarkable work is that of 
Looss (1905-1911) on the anatomy of the hook-worm ( Agchylostoma 
duodenale). of Goldschmidt (1908-1911) on the nervous system of 
Ascaris, and of Martini (1908 and 1909) on the sub-cuticula and lateral 
fields of Nematodes. Looss’ monograph is probably one of the most 
exhaustive ever written on a single species. Goldschmidt’s work is no 
less remarkable. He has traced out the entire nervous system of 
Ascaris lumbricoides and A. megalocepliala to its finest ramifications, 
and has shown that it is constant in arrangement. He has also been 
able to show that the nerve cells in Ascaris do not multiply but simply 
increase in size as the animal grows older. Another paper which appears 
worth mentioning here is that of De Baillon (1911) on the muscle fibres 
of Ascaris. 
Passing on now to a consideration of the bionomics of these forms 
and dealing first with the early life-history we find that several 
interesting matters have been investigated. For instance there is the 
discovery of the intermediate host of the Japanese liver-fluke ( Clonorchis 
endemicus ) by Kobayashi (1910 and 1911). Some of the credit of this 
discovery is due to Askanazy (1906). This fluke passes its intermediate 
stage encysted in certain fresh-water fishes and infection is acquired by 
eating these. There is also the discovery of the mode of infection of 
the Japanese blood-fluke (Schistosomum japonicum) by Katsurada and 
Hashegawa (1910). It is some years since Looss advanced the hypothesis, 
based on circumstantial evidence, that the blood-flukes have no inter¬ 
mediate host and that infection takes place through the skin. The 
work of Katsurada and Hashegawa has demonstrated experimentally 
the correctness of Looss’ views. Perhaps the most important other 
contributions to Trematode development is that of Haswell (1909) on 
