26 PROTOZOA AND DISEASE 



fever, is caused by the rapid asexual multiplication (schizogony) of 

 the parasites within the red corpuscles. In the corresponding phase 

 of infection of birds by T. noctucz the asexual parasites attach them- 

 selves to the surface of the red corpuscles, as shown in Fig. 7. The 

 mobile periods occur at night-time, and the flagellated forms are 

 met with chiefly in the spleen and bone-marrow. The periods of 

 attachment and growth, and of free swimming in the plasma, are 

 repeated for six days ; and when the parasites have attained their 

 full growth they detach themselves finally, and, swimming freely in 

 the plasma, undergo repeated longitudinal divisions, which result 

 in the blood being charged with small parasites, which then begin 

 to diminish in numbers. 1 The remaining previously asexual forms 

 now become differentiated into males and females, and as such pass 

 into the intestine of any gnat that may suck the bird's blood. 



As to those males and small females that entered the owl's blood 

 from the gnat with the asexual forms, whose career has just been 

 traced, the males die off at once, whilst the females enter red 

 corpuscles, losing their flagella, to assume the gregarinoid form 

 already mentioned as occurring in the gnat. 



Before leaving this subject we may note the structure of the 

 nucleus in the largest free trypanosome to the right of Fig. 7. 

 We see there the chief nucleus containing chromatin filaments, 

 and at the base of the flagellum a denser and smaller body, the 

 blepharoplast, which is connected by a filament with the chief 

 nucleus. By comparing the living organism with stained prepara- 

 tions, Schaudinn found that what appears in the gregarinoid phases 

 to be a nucleolus becomes amoeboid, and its chromatin mixes with 

 that of the nucleus, as the first step in the change to the flagellate 

 phase. The mixed chromatin then divides into two parts, the larger 

 remaining as the principal or trophonucleus, and from the smaller 

 or kinetonucleus, which remains attached by a filament 2 to the 



1 This diminution may be caused either by phagocytosis or from some of the 

 parasites leaving the blood to become gregarinoid in the tissues. 



2 The thickness of this filament is slightly exaggerated in Fig. 7. Among the 

 locomotor organelles are what may be called muscular strue (myonemes). In 



