286 
SCOTT'S LAST EXPEDITION 
[May 
weights being a scrap or two of leather and five hymn- 
books. Hitherto we have been only able to muster seven 
copies ; this increase will improve our Sunday Services. 
Wednesday , May 24. — A quiet day with northerly 
wind ; the temperature rose gradually to zero. Having 
the night duty, did not go out. The moon has gone and 
there is little to attract one out of doors. 
Atkinson gave us an interesting little discourse on 
parasitology, with a brief account of the life history of 
some ecto- and some endo-parasitcs — Nematodes, Tre- 
matodes. He pointed out how that in nearly every case 
there was a secondary host, how in some cases disease 
was caused, and in others the presence of the parasite 
was even helpful. He acknowledged the small progress 
that had been made in this study. He mentioned anky- 
lostomiasis, blood-sucking worms, Bilhartsia (Trcmatode) 
attacking bladder (Egypt), Filaria (round tapeworm), 
Guinea worm, Trichina (pork), and others, pointing to 
disease caused. 
From worms he went to Protozoa — Trypanosomes, 
sleeping sickness, host tsetse-fly — showed life history 
comparatively, propagated in secondary host or encysting 
in primary host — similarly malarial germs spread by 
Anopheles mosquitoes — all very interesting. 
In the discussion following Wilson gave some account 
of the grouse disease worm, and especially of the interest in 
finding free living species almost identical ; also part of 
the life of disease worm is free living. Here we approached 
a point pressed by Nelson concerning the degeneration 
consequent on adoption of the parasitic habit. All 
