110 TIMOTHY RICHARDS LEWIS. 



the blood of a rat which, at first sight, I took to be of the 

 nature either of vibrions or spirilla. The blood when transferred 

 to the microscope appeared to quiver with life, but for some con- 

 siderable time nothing could be detected to account for this 

 animated condition, as the blood-corpuscles were somewhat 

 closely packed. On diluting the blood with a half per cent, 

 solution of salt, motile filaments could be seen rushing through 

 the serum, and tossing the blood-corpuscles about in all direc- 

 tions. Their movements were of a more undulatory character 

 than are the movements of spirilla, and the filaments were 

 thicker, more of a vibrionic aspect. They were pale, translu- 

 cent beings, without any trace of visible structure or granularity ; 

 but, as their movements were so rapid, exact information as to 

 their microscopical characters could not be ascertained at the 

 time. The slides were therefore placed under a bell-glass until 

 these should diminish. 



On the following morning the activity of the filaments was 

 much less. Their movements were more restricted and more 

 undulatory in character, and the blood-corpuscles, having be- 

 come somewhat agglutinated, had apparently squeezed out the 

 organisms, so that the latter occupied the serum-areas of the 

 preparations. After watching their movements for some time 

 under a Hartnack's No. 9 immersion objective, it was observed 

 that every now and then blood-corpuscles, some considerable dis- 

 tance from any visible motile filament would suddenly quiver. On 

 carefully arranging the light it was eventually observed that this 

 movement was due to the existence of a very long and exceed- 

 ingly fine flagellum, apparently a posterior flagellum, as the 

 organisms seemed, generally, to move with the thicker end 

 forwards — the flagellum being seen following it, and lashing the 

 fluid during the moment it remained in focus. I have not been 

 able to detect any flagellum at the opposite end. The greater 

 number of the figures reproduced in the woodcut represent 

 these organisms as they are observed a few hours after the 

 blood has been obtained, when their movements are not so 

 rapid, and the flagellum becomes recognisable. They may some- 

 times be kept alive for two or three days, but generally the 

 greater portion will have died within twelve or twenty-four hours ; 

 and not only have died, but also disappeared from view. 



When very carefully watched, the plasma constituting the 

 thicker portion of their substance may be seen suddenly to swell 

 out at certain places — sometimes so as to divide the " body " into 

 two parts, as shown in the middle figure ; at other times two or 

 three such constrictions and dilatations may be detected, the dila- 

 tations being, possibly, observable only on one side. At other 

 times they assume an arrow-shaped aspect, as shown in the 



