488 A MANUAL OF BACTERIOLOGY 



A trypanosome has a slender, flexible, flattened body, one 

 extremity of which is pointed, the other passes into a single flagellum. 

 A delicate undulating membrane passes along one edge of the body. 

 The organism lives in the plasma, in which it is actively motile, the 

 flagellated end being usually anterior, and measures 15-30 /*, or 

 even 40-50 /*, in length. The protoplasm of the organism is finely 

 granular, and near the centre of the body is a large macronucleus, 

 and generally between it and the non-flagellated end is a smaller 

 micronucleus or blepharoplast. From the latter a chromatin 

 filament starts, runs along the free edge of the undulating membrane 

 and passes into the flagellum. Reproduction takes place by longi- 

 tudinal division, occasionally probably by transverse division, and 

 amoeboid and plasmodial masses may be found in the internal 

 organs and bone -marrow. The trypanosomes have great mor- 

 phological similarity, which renders them practically indistinguish- 

 able by structural characters. They can usually be differentiated 

 into three forms indifferent, male, and female which in some 

 cases may all occur together, but only become fully differentiated 

 in an invertebrate host. The males are slender, active, only slightly 

 granular, and with an elongated nucleus ; the females are bulky, 

 sluggish, granular, and have a rounded nucleus ; the indifferent 

 forms are intermediate. The males usually soon die off unless they 

 conjugate ; the indifferents are more hardy, the females most so. 

 The sexual forms conjugate in an invertebrate host, but if the males 

 have died off, both male and female forms may be reproduced from 

 the females by a process of parthenogenesis. 



Trypanosoma Gambiense 



In human trypanosomiasis and sleeping-sickness of 

 West and Central Africa, a trypanosome Tr. Gambiense 

 is the causative agent (Plate XXI. a). It is usually 

 present, though scanty, in the blood, but can often be 

 found in numbers in the fluid aspirated from the enlarged 

 cervical glands. In the later stages, when cerebral 

 symptoms ensue, it is found in the cerebro-spinal fluid, 

 but scantily, centrifuging being necessary in order to 

 demonstrate the parasites. The Tr. Gambiense is patho- 

 genic to monkeys, and to a less extent to white rats and 

 guinea-pigs. Cattle and certain antelopes and other wild 



