422 



TRYPANOSOMIDJE 



enlarged lymphatic glands, by scarification of the eruption, or by 

 puncture of the spinal canal, if the case is one of sleeping sickness. 



Salvin, Moore, and Breinl have, however, investigated the life- 

 cycle in the rat, in which, after inoculation, the parasites increase 

 to a maximum in the peripheral blood, and then decline gradually 

 to nil, at which they remain for a period— the latent period — and 

 then increase again in numbers and reappear in the peripheral blood. 



Their investigations give the following results : The parasite may 

 grow to a fair size, and then divide into two by simple fission, and 

 this may be repeated till the blood is swarming with them. When 

 this is the case, a relativel}^ thick band, said by Swellengrebel to be 

 composed of melachromatic or volutine granules (axial filament), 

 such as that described by Miss Robertson in T. mjce and by 

 Prowazek in T. lewisi, grows from the kinetonucleus down the 

 endoplasm till it reaches or even passes the nucleus, or it may 

 coil on itself, but eventually is connected with the trophonucleus. 





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Fig. log.— Castellanella castellanii. Chart of Lengths. 



The trypanosomes now decrease in numbers in the peripheral 

 blood, and are found in the lungs, spleen, and bone-marrow. In 

 these organs the protoplasm becomes detached from the periphery 

 of the nucleus, which lies in a clear space. The nucleus contracts, 

 and a large clear vesicle forms in connection with it, and around 

 both a cytoplasmic sheath is formed. The rest of the cell body 

 now disintegrates, and the flagellum with the kinetonucleus may 

 be seen lying detached. These bodies now become lodged in the 

 spleen and bone-marroW, where they remain intact for a period of 

 ten days or more— through the whole of the negative or latent period 

 when the trypanosomes are missing from the blood of the infected 

 rat. Moore and Breinl, therefore, call them latent bodies. They 

 consist of a flattened nucleus, containing a centrosome, and attached 

 to a vesicle, the whole being surrounded by a ring of cytoplasm. 

 This latent phase has been confirmed by Fantham. 



Just before the reappearance of the trypanosomes in the pen- 



