GENUS TRYPANOSOMA. 219 



Trypanosoma sanguinis, Gruby. Pl. I. Figs, i and 2. 



Body compressed, semilunate, twisted ; the convex border membranous 

 and undulating, with its margin deeply toothed ; the posterior extremity of 

 the body portion pointed and curved inwards, the opposite one produced 

 into a long tag- or tail-like appendage which almost equals in length the 

 remainder of the body ; surface of the body coarsely striate longitudinally ; 

 cndoplasm or parenchyma slightly granular; endoplast ovate, central. 

 Dimensions, 1-600". 



Hab. — Blood of the frogs, Rajia esailenta and R. tcmporaria. 



This species was first introduced to scientific notice by Gruby, who described 

 and bestowed upon it the name here given in the ' Comptes Rendus ' for November 

 1843. More recently this animalcule has been figured by Professor E. Ray 

 Lankester in the ' Quarterly Journal of Microscopical Science' for October 187 1, 

 under the title of Undtdina nviamm, its identity with Gruby's type being, however, 

 subsequently admitted. 



Professor Lankester's account given of the characteristic aspect and movements 

 of this singular animalcule, in the serial quoted, is as follows : — " In making examina- 

 tions of the blood of frogs, I have now and then met with the interesdng litde 

 parasite drawn inthe woodcut. When I first saw it, in some blood from a frog last 

 summer, I took it for a very active white blood-corpuscle, since it is a very little 

 smaller than one of the red corpuscles of the frog's blood. On using, however, a 

 higher power (No. 10a immersion, of Hartnack), I made out its infus'orial nature, 

 though, on account of the great activity of its movements, I was long uncertain as 

 to the nature of its locomotive organs. Numerous specimens occurred in the blood 

 of a frog {Rana escideiita), examined at Leipzig in March last, and by the use of a 

 small quantity of acetic acid vapour I was able to kill the litde creature without 

 injuring it, and then to make out its structure. It was seen to be a minute pyriform 

 sac, with the narrower end bent round on itself somewhat spirally, and the 

 broader end spread out into a thin membrane, which exhibited four or five folds, 

 and was produced on one side into a very long flagellum. The wall of the sac was 

 striated coarsely, as in Opalina ; and the direction of the striaj on the two sides of the 

 sac, as seen one through the other, showed that the small end of the sac was twisted 

 as well as bent over on itself A pale, clear nucleus and a very {q\v granules were 

 also seen. In life the broad membrane undulates vigorously in a series of waves, the 

 flagellum taking part, and presents then a deeply toothed appearance. The move- 

 ments produced by the activity of this membrane tend to urge the animal in a wide 

 circle. The opposite extremity of the sac twists and untwists itself to a small 

 extent also during life. The series of waves of the undulating membrane are not 

 incessandy in one direction ; after a certain time they change to the opposite 

 direction, and then resume their original direction, an alternation of from right to left, 

 and from left to right being kept up. When minute traces of acetic acid vapour are 

 passed into the gas-chamber where this infusorian is, it soon becomes affected ; the 

 undulations become deranged, starting from both ends simultaneously and meeting 

 in the middle, and at length ceasing." 



Trypanosoma Eberthi, S. K. Pl. I. F.os. 3-6. 



Body flattened, and semilunate when at rest, its convex membraniform 

 border serrated or presenting a beaded aspect ; straight, lanceolate, and 

 pointed at each extremity when in motion, not produced at either end into 

 a tag-like prolongation ; the membranous border often spirally convolute 



