56 PilOFESSOB E. KAY LANKESTER, 



be the readiest means of obtaining a preparation showing speci- 

 mens of the Drepanidium^ though a few were also observed in 

 the blood. 



I am able to confirm completely Dr. Gaule's account of the 

 remarkable movements exhibited by the parasites when the 

 preparation containing them is warmed to about 35° C. on the 

 stage of the microscope. These movements would indeed be 

 very extraordinary were we dealing with anything but an 

 independent protoplasmic organism. To the zoologist, accus- 

 tomed to the observation of the simpler forms of life, they 

 present nothing paradoxical. Probably under certain circum- 

 stances which recur in the natural state these parasites exhibit 

 the active movements which I have only, as yet, succeeded 

 in witnessing when the temperature is artificially raised to 

 that point which is known to be most favorable in general to 

 the activity of contractile protoplasm. The movements are 

 caused by an alternate bending and straightening of the curved 

 and spirally twisted body of the Drepanidium. They are 

 certainly 7iot caused by any attached filament of protoplasm in 

 the form of a flagellum (either '' tractellum " or " pulsellum "), 

 though, as seen in my original figure here reproduced (fig. 4), 

 and in the specimens examined this year by me, occasionally a 

 very fine motionless filament, or even two, may be attached to one 

 end of the Lrejmnidmm. 



The movements of the Drepanidium cease altogether when 

 the preparation containing it is heated to a temperature of 

 70° C., a fact tending very strongly to establish (what there is 

 no reason of another kind for doubting) that the movement is a 

 " vital " one, that is to say, depends on the substance of the 

 BrepanuVmm being in that physical condition which we call 

 " living,^' and which, in most cases, is irrevocably disturbed by 

 exposure to a temperature of 70° C. 



Like many other minute organisms {e.g. certain Bacteria), 

 Drepanidium is probably motionless for long periods under 

 normal circumstances, and has an active period which may be 

 induced by a favourable rise of temperature. 



Affinities of Drepanidium. — Since my first notice of Dre- 

 panidium our knowledge of the Gregarinidse and their allies, or 

 as Rudolph Leuckart has very aptly termed them, the 

 " Sporozoa," has been greatly extended, chiefly through the pub- 

 lications of Eimer (' Psorosperinien,^ Wurzburg, 1870), Aitnee 

 Schneider (' Archives de Zoologie experimentale,'' vol. iv, p. 493, 

 1875), and of Butschli (' Zeitschr. wiss. Zoologie,' vol. xxxv, pp. 

 384 and 629, 1881). 



It has now in fact become evident that the Sporozoa are at a 

 certain period of their life-history very usually cell parasites. 



