C. A. Hoare 
69 
Unfortunately, on account of the difficulty of obtaining live “keds,” owing 
to the operation of the dipping laws in England, my experiments could not be 
conducted on as wide a scale as desired, but had to be limited to the study of 
certain points in the life-history and behaviour of C. melophagia and to attempts 
at culture of trypanosomes from the sheep’s blood, and artificial infection of 
other mammals with these flagellates. 
Whilst this work was in progress, several publications by Noller (1917, 
1919, 1919 a, 1920) came to hand from Germany. The author appears to have 
been studying this subject for several years. By using special culture media 
and methods, he succeeded not only in cultivating trypanosomes from the 
sheep’s blood, but also in bringing about the transition from the crithidia 
forms to trypanosomes in vitro, thus establishing the identity of the two forms 
without any doubt. The trypanosome received the name of Trypanosoma 
melophagium Flu, 1908. 
I had at my disposal four sheep 1 , from which blood-cultures were made 
and kept at 24° C. and at 30° C., according to Noller’s methods (1919, 1919 a) 
in slightly alkaline bouillon. I did not succeed in cultivating any trypano¬ 
somes from the blood of these sheep, although they were infected with “beds’' 
containing flagellates in their guts. As it was impossible to obtain new material, 
and especially very young lambs, experiments on which might have been more 
fruitful, I was compelled to postpone this part of the work in the hope of being 
able to continue it early in the spring, when conditions are more favourable. 
As the morphology and development of C. melophagia in the gut of Melo- 
phagus ovinus have been studied and described in detail by other authors, I 
have directed my attention only to certain points that remained obscure in 
their description. One question is of especial importance. Flu (1908), Swingle 
(1909, 1911) and Porter (1910) claimed that these flagellates are transmitted 
to their offspring hereditarily, the flagellates penetrating into the ova, and 
thence into the developing embryo. The weak point in their description is the 
fact that the forins described and depicted by the three authors named have 
nothing in common with each other. Each author gives a different picture of 
the “hereditary” forms found, and with the exception of Porter’s figures, most 
of them bear no resemblance to any of the forms which insect- or haemo- 
flagellates usually assume. Porter claims to have actually seen the flagellate 
forms of the Crithidia penetrating through the eggs of the “ked,” losing their 
flagella there and passing into the “resting stage.” 
I have examined a fair number of ova and pupae of the sheep-ked both in 
sections and in smears, and have employed Porter’s technique in the latter 
case, but have failed to find any forms which could be interpreted as stages of 
a flagellate organism. In this respect my observations agree with those of 
Chatton and Delanoe (1912) and Cauchemez (1912), who have also failed to 
1 I wish to acknowledge my indebtedness to Mr J. B. Buxton, F.R C.V.S.. of the Wellcome 
Physiological Research Laboratories, for kindly supplying me with the necessary material for my 
work. 
