The blood-corpuscles are about 1/5000th of an inch each in diameter.
The creature drawn in our fig. 50 is, then, the typical trypanosome. It is this which the medical investigator looks for in his human or animal patients; it is this which he has regarded as the sign and proof of infection. Experiments have shown that, though so much alike in appearance in the different diseases we have named, yet each trypanosome has its own properties. Human blood-serum is poisonous to one and not to another; an animal immune to one is not immune to another. At present no treatment has been discovered which will destroy the parasites when once they have effected a lodgment, or act as an antidote to the poison which they produce in the infected animal or man. But the fact that in some cases an animal may become immune to the attack of the parasite which usually is deadly to its kind, gives hope of an eventual curative treatment for trypanosome infection; as does also the fact that the serum of some animals acts as a poison to trypanosomes which flourish in other animals.
With regard to immunity, it must always be remembered that we are liable to confuse two different conditions under this one term. An animal may be said to be immune to blood-parasite because that parasite is actually unable to live in its blood. On the other hand an animal is often said to be immune to a parasite when the parasite can and does flourish in its blood or tissues but produces no poisonous effect. A more precise nomenclature would describe the attacked organism in the first case as “repellent,” for it repels the parasite altogether; in the second case as “tolerant,” for it tolerates the presence and multiplication of the parasite without suffering by it.
We have yet to learn a good deal more as to the repulsion and the toleration of the trypanosome parasites by mammals and man. Still more have we to learn about the life-history of the trypanosome. At the moment of writing, absolutely nothing has been ascertained as to the life-history of the trypanosome of mammalian blood, except that they multiply in the blood by longitudinal fission. Our ignorance about them is all the more serious since other trypanosomes, discovered by Danilewesky in birds, have been studied and have been shown to go through the most varied phases of multiplication and change of size and shape, including a process of sexual fertilisation like that of the malaria parasite, to which, indeed, it now seems certain the trypanosomes are very closely allied.
It is to Dr. Schaudinn[26], that we owe a knowledge of some most extraordinary and important facts with regard to the trypanosomes parasitic in the blood of the little stone-owl of southern Europe (Athene noctua). These facts are so remarkable that, were Dr. Schaudinn not known as a very competent investigator of microscopic organisms we should hesitate to accept them as true. Supposing, as is not improbable, that similar facts can be shown in regard to the trypanosomes of mammalian blood, the conclusions which our medical investigators have based upon a very limited knowledge of the form and life-history of the trypanosomes occurring in diseases such as sleeping sickness, surra, and nagana, are likely to be gravely modified, and practical issues of an unexpected kind will be involved.
As has already been pointed out in this article, the British Government has no staff of public servants trained to deal with the world-wide problems of sanitation and disease which necessarily come with increasing frequency before the puzzled administrators of our scattered Empire. There is no provision for the study of the nature and history of blood-parasites in this country, that is to say, no provision of laboratories with the very ablest and exceptionally-gifted investigators at their head[27]. We play with the provision of an adequate army, officers, and equipment to fight disease, which annually destroys hundreds of thousands of our people, much as barbarous states or bankrupt European kingdoms play with the provision of an ordinary army and navy. Their forces exist on paper, or even in fact, but have no ammunition, no officers, and no information; and there is no pay for the soldiers or sailors. Dr. Schaudinn, on the other hand, carried on his researches as an officer of the German Imperial Health Bureau of Berlin; and the account of them was published in the official Report of that important department of the German imperial administrative service three years ago.
