1917] Kofoicl-Swezy: On the Orientation of Erythropsis 95 



not all, of these eases the period of observation was brief in as much 

 as the animal quickly drops its prod and undergoes cytolysis shortly 

 thereafter, when exposed to the stimulus of the brilliant illumination 

 of the microscope. 



The first individual was found by the eminent Russian biologist, 

 Elie Metschnikoff, who found it amid plankton debris taken off 

 Funchal in the Madeira Islands in 1872. In a brief note (in Russian) 

 he (1874) called attention to its possible relationships to the Suctoria, 

 but neither described nor figured it. Ten years later the greatest of 

 German protozoologists, Professor Richard Hertwig, then of Bonn 

 University, found a single individual in the plankton of the Mediter- 

 ranean at Sorrento. It dropped its prod soon after its capture, but 

 was thereupon fixed in osmic acid and preserved in mutilated and dis- 

 torted form as a microscopical preparation. From this abnormal frag- 

 ment Hertwig (1884) described ^^Erythropsis agilis, eine neue Pro- 

 tozoe," making the comparison of the prod to the stalk, and noting 

 the similarity of its anterior part to the peristomal region of a vorti- 

 cellid ciliate. However, he explicitly notes the absence of cilia and the 

 presence of a spiral filament wound about the anterior end. He did 

 not, however, suggest any relationship of his unique organism to the 

 flagellates or to the Dinoflagellata. 



Immediately upon the publication of Hertwig 's account, the veteran 

 zoologist, Carl Vogt, of Geneva, attacked (1885a) the validity of the 

 organism and called upon all zoologists to deny it admission to the 

 category of beasts on the ground that it was only a detached zooid of 

 a marine vorticellid, Spastostyla sertulariarum Entz, which had eaten 

 the eye of a medusa, Lizzia or Nausithoe. Hertwig replied (1885) 

 clearly setting forth the characters of Erythropsis which made Vogt's 

 interpretation untenable; but the latter was unconvinced, returning 

 (1885&) to the fray with a deadly array of parallel figures in which he 

 reproduced Hertwig 's figure with the evidence of the error by Hert- 

 wig made the more convincing by the substitution in his copy of the 

 figure of Erythropsis of a row of membranelles for Hertwig 's spiral 

 thread and the introduction of an axial fibre in the stalk-like prod or 

 tentacle. 



This discussion brought Metschnikoff (1885) to the support of 

 Hertwig who recalled his brief note (1874) on the organism of a decade 

 prior, expressed his confidence in the authenticity of the organism and 

 allied it with the suctorian Ophryodendron. 



The cloud of suspicion thus cast upon Erythropsis may or may 



