266 
The animal trypanosomes we found in the Congo approach 
'Trypanosoma dimorphon most nearly in morphology and animal 
reactions. On these grounds we identify them with that species. 
Broden (3) believes that there are two varieties of trypanosomes, at least, in 
the Congo. One of these, corresponding to our “ tadpole ” forms, he calls T. cngh 
lense , while the other he assimilates with T. vivax , described by Ziemann in the 
Cameroun. At Leopoldville he found a cow with the two varieties of trypano¬ 
somes. From the fact that in the sub-inoculations he found only parasites 
corresponding to his small forms, he concludes that the animal was suffering from 
a double infection. It is possible that the explanation suggested above may apply 
in this case. Broden also remarks, in considering the identity of the small form, 
that Dutton and Todd were unable to discover their trypanosome in Gambian 
cattle. That their examinations were insufficient has been demonstrated by 
Captain A. G. Todd, A.V.C. (13), who has since found trypanosomes in these 
animals. 
In the Soudan, Balfour (14) found a trypanosome in cattle which bears 
considerable resemblance to the “tadpole’' type found in the Congo. Five animals— 
two monkeys, two rabbits and a dog — were sub-inoculated with small quantities of 
blood, but trypanosomes were never seen in any of them. As the author states, the 
number of experiments is too small for any dogmatic opinion to be given as to the 
non-susceptibility of these animals. It should be again noted here that of many 
animals inoculated from cattle by us only one rat became infected. Balfour s 
trypanosome was named 7 ’. nanurn by Laveran. Is it not possible that further 
work on this parasite may show that it is merely the tadpole form of T. dimorph^. 
In addition to cattle, Balfour found mules infected, but in these the trypanosomes 
were frankly of the 7 '. dimorphon type (stumpy and long forms). In these the long 
slender trypanosomes have a free flagellum. 
In French Guinea Martin (15) found that most of the domestic animals suffered 
from one of two trypanosomiases. Of these, the most frequent was due to 
Trypanosoma dimorphon , and it is interesting to note that in a sheep the trypano¬ 
somes had a long free flagellum, thus once again bearing out Dutton and Todds 
observations. In sub-inoculations, however, the flagellum was lost as in Dutton 
and 1 odd’s strain of T. dimorphon. Another interesting point is that in cattle Martin 
noted that occasionally' only one type of the parasite was present, most often the 
long form. 
Quite recently Laveran (16) has described a trypanosome found in sheep 
coming from Sdgou on the Upper Niger. This trypanosome presents many of the 
characteristics of T. dimorphon , but from the fact that a sheep which had recovered 
Irorn the disease, and had afterwards resisted a second inoculation of the same 
strain, became infective when inoculated with Trypanosoma dimorphon, Laveran 
concludes that it is a separate species, and accordingly names it Trypanosome 
7 rypanosoma congolense. Trypanosoma nanum and T rypanosow 
vivax, at least, of other African trypanosomes, present marked 
affinities with Trypanosoma dimorphon. If they are identical the 
dist ribution of Trypanosoma dimorphon is very wide. 
* At this juncture 
described by Koch (20, 
it is well to consider the variations in form 
page 121) to occur in T. brucei. 
and virulence 
