General Morphology and Biology. 799 



ameboid forms result, wMch. contain two or more chromatin 

 substances, and only later separate into more individuals. 



Besides this simple mode of multiplication, a sexual propagation, 

 or a special development is considered possible in the transmitting in- 

 sects as intermediary hosts (Ziemann, Prowazek, Koch, Schaudin, 

 Stuhlmann, Kleine and others). 



This opinion is based principally on the investigations of the intes- 

 tinal contents of stinging flies (Glossinae), infected with trypanosomes, 

 in which besides typical, broad forms rich in plasma, very thin forms 

 are found containing only a small quantity of plasma with elongated, 

 nucleus, and sometimes without flagella. According to Koch the former 

 are considered as females, the latter as male trypanosomes, and they are 

 supposed to copulate with each other. -According to Kleine 's investiga- 

 tions of sleeping sickness, the development is supposed to extend over, 

 several weeks, so that infected flies may be capable of causing infection 

 for that period. 



According to the experimental results of Battaglia, obtained by a study of 

 the multiplication of the Trypanosome Lewisi and the Trypanosome Brucei, a mul- 

 tiplication by sporogeny occurs also in the blood of the same animaf, inasmuch as 

 after an infection with small motile, intra-globular ameboid forms, first similar 

 extra-globular forms develop, later larger, roundish or pear-shaped unflagellated 

 forms, and only from these finally result the fully developed forms, and these 

 then multiply by longitudinal division. This conception is supported by the 

 experience that it is possible to transmit the disease artificially with filtrates of 

 infected blood, after passing it through Berkefeld (not Eeichel or Chamberland) 

 filters. 



Staining. The trypanosomes are even with slight magnification 

 easily recognizable by their peculiar form, and by their lively snake- 

 like movements. They stain uniformly with the ordinary aqueous anilin 

 dyes, while the structure may be brought out by the use of Roman- 

 owsky's or a similar stain by which the nucleus, the Blepharoblast and 

 the flagella appear pale red (chromatin stain) and the plasma pale blue. 



Eecently Giemsa's stain is used almost exclusively with the azure prepared 

 by him in pure form. Staining fluid: to each cc. of distilled water, one drop of 

 Giemsa's- solution, always to be freshly, prepared. Staining of the smear prepara- 

 tion which has been fixed in alcohol or alcohol-ether (aa) for 15-20 minutes, then 

 washing in running water. 



Cultivation. Novy & McNeal succeeded in cultivating the try- 

 panosomes of rats and later also those of nagana on agar to which had 

 been added about 50% of blood, at a temperature of 25° -34° C. In the 

 cultures non-motile forms develop 1-2, up to 50-60^ long, and the first 

 of them may pass through porous filters. Trypanosomiasis was produced 

 artificially in rats with Berkefeld filtrates of cultures. Since then the 

 cultivation of other disease-producing trypanosomes was successfully 

 carried out in a similar manner (Irikura cultivated them in blood 

 bouillon of 1/2-2:10). 



Tenacity. The parasites can be kept alive outside of the animal body for 

 several days, but only in defibrinated blood, to which pure serum is added. Cool 

 temperature usually lengthens their lives, while against higher temperatures (43° 

 and over) and chemical influences they are in general very sensitive. 



The differentiation of the various types depends, aside from 

 marked deviations in the form of the trypanosomes, almost ex- 



