Collected papers on trypanosomiasis / by Sir David Bruce and others.

  • David Bruce
Date:
[1909-1911]
Catalogue details

Licence: Public Domain Mark

Credit: Collected papers on trypanosomiasis / by Sir David Bruce and others. Source: Wellcome Collection.

    49/268 (page 517)
    In our experience, the long narrow forms, described by some observers as “ male ” forms, are exceedingly rare, and it seems impossible to ascribe to to them any very important role in the process of development. Crithidia- like forms are also exceedingly rare—that is, forms with the micronucleus close to or anterior to the nucleus. Types of Trypanosoma gambiense found in the Salivary Glands.—On referring to Table I it will be seen that trypanosomes did not appear in these glands until the twenty-fifth day, but that after this time they were usually present. In our opinion, this invasion of the salivary glands is of the greatest importance in the history of the development of Trypanosoma gambiense in Glossina palpalis. Here it may be parenthetically remarked that, because one kind of development takes place with one species of trypanosome and one species of tsetse fly, it by no means follows that the same thing will occur either with another species of trypanosome or another species of fly. Each combination must be worked out separately and nothing left to analogy. Trypanosoma vivax and Glossina palpalis afford a striking example of this. In the development of Trypanosoma gambiense in Glossina palpalis one circumstance, which we think of prime importance, emerges, and that is, that in the salivary glands, and here alone, the trypanosomes are found to revert to the normal blood-type. It must not be imagined, however, that the salivary glands show no other forms but this blood-type. On the contrary, there are many other forms seen; but here only are found trypanosomes apparently identical with the short and stumpy forms found in the blood. What causes or leads up to this reversion to the blood-type in the salivary glands is quite unknown, but, as will be seen later, the Glossina palpalis does not become infective by biting until this invasion of the salivary glands takes place. How the trypanosomes find their way into the salivary glands is also quite unknown. It seems highly improbable that they pass from the alimentary canal by way of the salivary duct, and as they are never found in the body- cavity, it is also difficult to see how they .can make their way directly from the intestine to the abdominal portion of the salivary glands.