THE HAEMOFLAGELLATES 



253 



Central Africa. The earlier stages of the disease, when the parasites are 

 confined to the blood, are known as Try panosoma-i 'ever ; the later ones, after 

 the organisms have penetrated into the cerebro-spinal canal, constitute the 

 deadly malady of sleeping-sickness. The true, natural host is unknown. 

 T. equinum, Voges (Syn. T. elmassiani, Lign.). Length 22-25 /x, width 

 lJ-2 //,. Distinguished from all other forms by the minute size of the 

 kinetonucleus (Fig. 32, B). Hydrochoerus capybara is almost certainly a 

 natural host. Other well-known lethal parasites are : T. evansi (Steel), of 

 Surra in horses in Indo-Burmah (Fig. 32, c) ; T. equiperdum, Doflein (Syn. 

 T. rougeti, Lav.), the cause of Dourine in horses, transmitted naturally by 

 coitus (Fig. 32, D) ; T. theileri, Laveran, a very large form, often surpassing 

 50 p in length, which causes "bile-sickness" of cattle in the Transvaal 

 (T. transvaaliense, Lav., with the kinetonucleus near the middle of the 



Fio. 34. FlO. 85. 



T. johnstoni. g, deeply-staining granule at A Trypanosome from Sene- 



distal extremity of flagellar border, x 1500. gambian birds, x 1500. (After 



(After Button and Todd.) B. and T.) 



body (Fig. 33, C-E), has been shown to 

 be, in all probability, only a phase of 

 T. theileri) ; and T. dimorphon, Dutt. 

 and Todd, which gives rise to a trypcino- 

 somosis of horses in Senegambia. 



(6) Parasitic in birds. T. avium, 

 Danil., Lav. emend., probably the form 

 to which Danilewsky's original investi- 

 gations related, occurring in owls and, 

 according to Novy and M'Neal, in 

 various other birds. Length 35-45 //, 

 (Fig. 7, p). T. johnstoni, Dutt. and 



Todd. Length 36-38 /*, width li- fJ,. T. paddae. At x the base of the flagel- 

 This Tiarfldifp i<j an alpnrlpr na wlrnnQf lum is thickened prior to division. 



slender as almost x 1200 (After ThirouXt) 

 to justify the description spirochaeti- 



form (Fig. 34). From Estrelda. The opposite extreme of form is 

 seen in a Trypanosome, T. hannae, Pittaluga, originally described by 

 Hanna (2 5) from an Indian pigeon (Fig. 7, o) ; this is relatively 

 very broad, and has, moreover, a long, attenuated aflagellar extremity, the 

 latter character being not unusual in bird-Trypanosomes. On the other 



Fio. 36. 



