I2O DAVID D. WHITNEY. 



* 



amphiceros type possessing these two lateral spines while the 

 fertilized eggs from females reared in sodium silicate solutions 

 developed into young females of the Brachionus pala type lacking 

 these two lateral spines. 



3. The variety or species of rotifer, Brachionus amphiceros, 

 does not exist as a true variety or species, but is only one of the 

 polymorphic stages of Brachionus pala. 



4. Perhaps the polymorphic forms of this rotifer as it occurs in 

 pools and ponds during the year are produced by the varying 

 amounts of soluble siliceous substances in the water. 



5. The females of Brachionus amphiceros possessing the two 

 lateral posterior spines readily produced female parthenogenetic 

 eggs, male parthenogenetic eggs, or fertilized eggs according to 

 the supply of the green focd Chlamydomcnas. 



BIOLOGICAL LABORATORY, 

 WESLEYAN UNIVERSITY, 



MlDDLETOWN, CON'N. 



April 26, 1916. 



LITERATURE CITED. 



Langhans, Victor. 



'06 Asplanchna priodonta Gosse und ihre Variation. Arch. Hydrobiol. 



Planktonk., Bd. i, pp. 439-68. 

 Lauterborn, R. 



'98 Yorlaufige Mitteilungen tiber den Variationskreis von Anuraea cochlearis 



Gosse. Zool. Anzeiger, Bd. 21, pp. 597-604. 

 '04 Die cyklische oder temporale Variation von Anuraea cochlearis. Vehr. 



Nat.-Med. Ver. Heidelberg, N.F., Bd. 7, pp. 529-621. 

 Mitchell, C. W. 



'13 Experimentally Induced Transitions in the Morphological Characters of 

 Asplanchna amphora Hudson, together with Remarks on Sexual Repro- 

 duction. Journ. Exper. Zool., vol. 15. 

 Powers, J. H. 



'12 A Case of Polymorphism in Asplanchna Simulating a Mutation. Am. 



Nat., vol. 46. 

 Sachse, R. 



'12 Biologische Untersuchungen an Radertieren in Teichgewassern. Sonder- 

 abdruck aus Internationale Revue der gesamten Hydrobiol. und Hydro- 

 graph. 

 von Wesenberg-Lund, C. 



'98 Uber danishche JRotiteren und iiber die Portpflanzunggsverhaltnisse der 



Rotiferen. Zool. Anzeiger, Bd. 21, p. 200. 



'10 Grundziige der Biologie und Geographic des Suswasser-Planktons. Son- 

 derabdruck aus Internal. Rev. d. gesam. Hydrobiol. u. Hydrograph. 



