920 Transactions of the Society. 



to Mitroplmnow that they were possibly the cytozoa described by 

 Gaule ; * but this idea was dismissed, by the fact that they were 

 found in blood to which no salt solution was added. Their size varied 

 from 30 to 40 /x in length and 1 to 1£ /x in width. At first their 

 rapid movements baffled examination, but as the rapidity lessened 

 there was the appearance of a curling movement in the body 

 portion and a swinging movement of the lash. The organism 

 moved in the direction of the lash, the anterior end of the body 

 being more pointed than the posterior, and gradually fining off into 

 the lash. When the body seemed to rest, the lash might be seen to 

 whip out in all directions. As the movement of the body gradually 

 diminished, it appeared to have a complicated screw form, the axis 

 of the screw corresponding to the body to which an undulating 

 membrane is fastened spirally. This could be distinguished when 

 the organism was dying, because the body in death contracted, and 

 the membrane then looked like a spiral addition. Thus the 

 organism consisted of a body, a spiral membrane, and a flagellum. 



With higher magnification the organism appeared to consist 

 of a refractive, strongly contractile protoplasmic substance, which, 

 when death occurred, formed a shapeless mass. In the same blood 

 two other forms were observed, one without a membrane, but 

 having two highly refractive spherules in the protoplasm, and 

 another with neither membrane nor flagellum, consisting of very 

 granular protoplasm with several refractive spherules, and capable 

 of protruding processes like pseudopodia. 



In the carp (fig. 195) the parasite is perceptibly larger, and 

 possesses an undulating membrane fastened along the edge of the 

 long body. When the body bent first towards one side and then 

 to the other, a wave-like movement was observable at the free edge 

 of this membrane. 



* In 1871 Prof. Lankester (Quart. Journ. Micr. Sci., xi. pp. 387-9) described 

 an organism which he had discovered in the blood of the frog (Rana esculenta). 

 It consisted of a minute pyriform sac with the narrower end bent round on itself 

 somewhat spindly, and the broader end spread out into a thin membrane, which 

 exhibited four or five folds and was prolonged on one side into a very long 

 flagellum. The wall of the sac was striated, nucleated, and granular ; the 

 membrane undulated during life, and the flagellum was also motile. It was 

 named Undulina ranarum, but subsequently recognized as identical with Trypano- 

 soma sanguinis described by Gruby (Coniptes Rendus, Nov. 1843). In the same 

 blood Lankester olso discovered little oblong bodies, in many cases attached 

 to the end of the red corpuscles, and suggested a genetical connection with 

 the Undulina. One or more motionless filaments were occasionally observed 

 attached to these bodies. Gaule (" Ueber Wiirmchen welche aus den Frosch- 

 blutkorperchen auswandern," Archiv. f. Anat. und Physiol., 1880, s. 57) sub- 

 sequently observed the same bodies, and regarded them as resulting from the 

 metamorphosis of the cells of the frog's blood. Gaule's observations were refuted 

 by Lankester in 1882 (Quart. Journ. Micr. Sci., xxii. pp. 53-65), the parasitic 

 nature insisted upon, and the organism named Drepanidiim ranarum. Lankester 

 suggested that they were probably the young stage of a sporozoon allied to 

 the Sarcocystis or to Coccklium. 



