PROTOZOA AFFECTING TRANSPORT 307 



now largely performed by mechanical apparatus, yet 

 even among these the horse finds a place. Motor 

 power has not yet wholly supplanted the horse and 

 mule in the moving of guns and similar implements 

 of warfare ; nor has it yet superseded the camel as a 

 means of crossing the shifting surface of the Sahara. 

 Yet these animals most used in transport may be 

 afflicted with trypanosomiasis in tropical and sub- 

 tropical countries. Even as near to England as Spain 

 and the South of France, trypanosomiasis in the 

 form of " dourine " can play havoc with the baggage 

 animals, particularly mules and horses, that cross 

 and recross the mountainous passes of the Pyrenees, 

 and are the main means of transporting local agri- 

 cultural produce between the two countries. The 

 " nagana " of Africa, due to Trypanosoma brucei, is 

 very serious, for it is spread by Glossina morsitans, 

 one of the most ubiquitous of tsetse flies. It is 

 invariably fatal to horses, donkeys, and dogs, and a 

 very small proportion of the cattle infected with it 

 recover. The problem of transport is serious in 

 some parts of India, Burma, Mauritius, and the 

 Philippines, for " surra," due to Trypanosoma evansi, 

 infects horses, mules, camels, and cattle alike, and 

 with fatal results. The biting flies Tabanus and 

 Stomoxys are responsible for its spread, and Mauritius 

 animals became infected by stock imported from 

 India. South American horse-breeding suffers be- 

 cause of the presence of T. equinum, that produces 

 the disease known as " mal de caderas." The exact 

 means whereby the malady is spread from horse to 

 horse is unknown, but it has been found that the 



