592 FAMILY: TRYPANOSOMIDiE 



2. Large compact individuals (Fig. 239, 12), more or less spherical or 

 ovoid in shape, with a longitudinally striated periplast, spherical nucleus, 

 and spherical kinetoj)last which lies near the nucleus. The undulating 

 membrane is well developed, while the axoneme usually terminates at the 

 anterior end. In some, however, there is a short flagellum. The posterior 

 end of the trypanosome is often rounded. 



3. Flat leaf-like forms (Fig. 239, 11), with rounded or pointed posterior 

 end, well-developed undulating membrane, and long flagellum. The 

 periplast is usually not striated. The nucleus is a long drawn-out structure, 

 the posterior end of which lies near the kinetoplast at the posterior end of 

 the trypanosome, while the other end terminates at the middle of the body. 



According to Noller, it is in the order given above that these forms 

 appear in the blood of the frog. Those of type 1 are undoubtedly 

 developed by growth from the tadpole form, which is of the same shape 

 but smaller. By a further growth and thickening the large solid forms of 

 type 2 are produced. Whether the leaf-like forms of type 3, with their 

 curious elongate nuclei, are developed from the solid forms in some way 

 or from those of type 1 through an increase in breadth and not in thickness 

 cannot be stated with certainty, but the latter would seem to be more 

 probable. The three types are not sharply marked off from one another, 

 as connecting links occur. It is thus evident that T. rotatorium of the 

 tadpole and frog exhibits a great variety of shape and form, and it is for 

 this reason that numerous synonyms have arisen. 



Susceptibility of Frogs and Other Animals.— Noller (19136, 1917), working 

 in Europe, has published accounts of inoculation experiments per- 

 formed with the trypanosome of frogs. The blood of tadpoles of Rana 

 esculenta infected with trypanosomes was inoculated into adult frogs, 

 which developed a larger infection of the forms characteristic of frogs 

 than they had before. Further inoculations were carried out with large 

 doses of cultural forms from blood-agar plates. Though the frogs had 

 already a small infection, they developed an enormous one which killed 

 them. The blood and organs were swarming with the large trypanosomes, 

 and this was especially marked in the kidneys, where veritable emboli of 

 these forms occurred. These infections were undoubtedly superimposed 

 on old-standing ones. Inoculation of R. temporaria, which is rarely found 

 naturally infected, with cultures of T. rotatorium derived from R. esculenta 

 led to a milder blood infection though the kidneys were found heavily 

 loaded with trypanosomes. The tree frog, Hyla arborea, was also infected, 

 a fact which suggests that T. hylce of Fran9a (1908c?) is actually T. rota- 

 torium. Two toads, Bombinator igneus, were inoculated with very large 

 doses of culture, and no infection took place. This species of toad 

 has never been found naturally infected with a trypanosome. Similar 



