November 21, 1913] 



SCIENCE 



727 



they are not yet quite sure of their place. 

 But they, nevertheless, although insecure 

 of their place in the books, produce grave 

 diseases, such as relapsing fever, tick fever 

 of man, the spirochetoses of horses, oxen 

 and birds, syphilis and yaws. They, with 

 the exception of the last two, are carried 

 by, and developed in, ticks and bugs; and 

 in tick fever the parasite is also found in 

 the nymph form of the tick, and this is 

 one of the rare instances of heredity of a 

 parasite. 



The spirochete of relapsing fever in man 

 was discovered by Obermeier in 1868, and 

 he died from inoculating himself with the 

 blood of a patient with the disease. He 

 was one of the first scientific martyrs; he 

 established our knowledge of the cause of 

 this disease at the expense of his own life. 



"We will now take a long jump to the 

 filarias. These are nematode worms, the 

 embryo forms of which live in the blood; 

 the parent forms, being too large to get 

 through the capillaries, live in many other 

 parts of the body. The larval form lives 

 in the body of some invertebrate — in a few 

 known cases in a mosquito, or in a crusta- 

 cean. The microfllarice were discovered by 

 Demarquay in 1863. Many of them show 

 a remarkable periodicity, some appearing 

 in the blood at an exact hour at night, and 

 some in the day, for which phenomenon 

 there is at present no satisfactory expla- 

 nation. 



Some are short, and some long, and some 

 are encapsuled, others not. Filarise cause 

 various diseases, probably elephantiasis, 

 and certainly enormous varicosities of the 

 lymphatics, chyluria, chylous dropsy, Cala- 

 bar swelling and certain tumors. 



We now come to the trypanosomes. 

 They are flagellated organisms, which are 

 the cause of many deadly diseases in men 

 and animals; such as sleeping sickness, 

 nagana (or tsetse-fly disease), surra, mal- 



de-caderas, dourine and others. They are 

 transferred from animal to animal by 

 biting flies, fleas, lice and leeches, in which 

 the sexual part of their life-cycle takes 

 place. The first one was seen in the blood 

 of a frog by Gluge in 1842. 



A type example is T. Lewisi in the blood 

 of a rat. This was discovered by Lewis in 

 1878, and is found in about 25 to 29 per 

 cent, of wild rats. Some die, but most 

 recover and become immune; it is a very 

 specific parasite, and can not be trans- 

 ferred to any other kind of animal. 



The T. Brucei, causing nagana or tsetse- 

 fly disease, probably exists in the wild 

 game of South Africa, much as the T. 

 Lewisi does in the wild rats, but when it 

 is carried by the tsetse-fly to domesticated 

 animals it kills them one and all in enor- 

 mous numbers. 



The T. Gamhiense, which causes sleeping 

 sickness, was first seen by Button in 1902, 

 and is carried by another species of tsetse- 

 fly. 



Nature attempts to fight against these 

 invaders by phagocytosis. The parasites, 

 however, multiply so rapidly that this 

 method of attack is not very effectual; it 

 can only be so in very early infections, and 

 probably it then often is, that is, before the 

 parasite has had time to start dividing. 

 At the present time the question of try- 

 panosomosis amongst man and animals is, 

 for many countries which have colonies, of 

 the greatest economic importance, so that 

 a great deal of work has been done in the 

 attempt to find a cure. A great many 

 drugs, new and old, have been tried, and 

 some good has been done. The first drug 

 which was found to be of service was ar- 

 senic, first in simple and then in complex 

 combination, and the sub-committee of the 

 Royal Society, formed for the purpose of 

 supervising experiments in this direction, 

 suggested the trial of antimony ia these 



