778 



SCIENCE. 



[N. S. Vol. VIII. No. 205. 



most signall}'. Yet both acid and alkali 

 decrease the power of resistance of Para- 

 mecia against this poison. Neither has 

 alkali a favorable action in case of poison- 

 ing by veratrin, although this, like KISTC 

 and atropin, has an alkaline reaction. 



We thus see that our theory also stands 

 this test successfully. As alkalies and not 

 acids have this property, it seems possible 

 that the destructive substances formed by 

 fermentation are acids. "Whatever may be 

 the real explanation, the fact remains true 

 that Paramecia are able to endure lack of 

 oxygen, high temperature and the action 

 of poisons like KNC and atropin for a 

 longer time in weak alkali solutions than 

 in neutral or acid solutions. 



William Zoethout. 



Hull Physiological Laboratory, 

 University of Chicago. 



LEIDY'S GENUS OUEABICEBA. 

 HISTORY. 



At a meeting of the Dublin Microscopical 

 Club, February 15, 1866, Mr. William 

 Archer exhibited specimens of Amceba villosa 

 (Wallich), calling special attention to the 

 presence of " a large and numerous tuft of 

 verj' long prolongations issuing from just 

 behind the villous patch. * * * He thought 

 it could readily be seen that these curi- 

 ous fasciculi were not composed of foreign 

 bodies either issuing from or penetrating 

 into the Amoeba, but were really linear pro- 

 longations of the Barcode itself. * * * This 

 observation, quantum valeat, seems possibly 

 to point to a still greater diiferentiation of 

 parts than has yet been observed in this 

 remarkable form. " * 



After nearly eight years, October 23, 

 1873, Mr. Archer again drew the attention 

 of the Dublin Microscopical Club to the 

 same condition in Amceba. He still con- 

 sidered the projections from the posterior 

 end to be prolongations of the body sub- 



*Quart. Jotirn. Micr. Soc, 6:190. 



stance, though the behavior (as regards 

 flow of contents, locomotion, etc.) was quite 

 that of an Amceba villosa.-^ 



In May of the year following. Dr. Joseph 

 Leidy, of the University of Pennsylvania, 

 found in the vicinity of Philadelphia a sin- 

 gular amoeboid creature carrying tufts of 

 caudal filaments, and gave a brief descrip- 

 tion of it in the Proceedings of the Academy of 

 Natural Sciences of Philadelphia, bestowing 

 upon it the name Ouramceba, in allusion to 

 its tail-like filaments, and distinguishing 

 several forms, f An abstract of this paper 

 published in the Monthly Mic. Journal, No- 

 vember, 1874, brought from Mr. Archer the 

 citation of his original notice of 1866, both 

 observers reaching the conclusion that they 

 had lighted upon the same creature.^ An 

 illustrated notice of the form by Dr. Leidy 

 appeared in the Philadelphia Proceedings of 

 1875. § In 1879 the Fresh-water Ehizopods of 

 North America was issued under the auspices 

 of the U. S. Geological Survey. Dr. Leidy 's 

 fiaal treatment of Ouramceba occurs in that 

 sumptuous volume. The points which bear 

 directly upon the thesis of the present pa- 

 per may be briefly summarized : 



1. The caudal filamentous appendages 

 alone excepted, Leidy remarked no differ- 

 ence between Ouramceba and A. proteus ; 

 while Mr. Archer regarded the form ob- 

 served by him as identical with A. villosa, 

 the filaments excepted. || 



2. " The mode of fixation of the caudal 

 filaments is difficult to comprehend. In a 

 detached tuft the root appeared to be con- 

 tinuous with a ball of homogeneous proto- 

 plasm."^ 



*Idem, 14:212. 



t Proceed. Acad. Nat. Sci. Phila., 1874, p. 78. 



t In 1874 Mr. Archer doubted the validity of the 

 proposed genus Ouramceba, although he thought the 

 filaments retractile. See Quart. Jour. Mic. Soc, 15 : 

 203 ; but compare Idem, 16 : 337. 



J Idem, 1875, p. 126 f. 



11 Fresh-Water Ehiz. N. Amer., p. 68. 



If Idem, p. 69. 



