A CONTRIBUTION TO THE LIFE HISTORY OF 

 AMCEBA PROTEUS LEIDY. 1 



LEON AUGUSTUS HAUSMAN, PH.D., 

 ZOOLOGICAL LABORATORY, CORNELL UNIVERSITY. 



It is only within the last few years that a connected life history 

 of Amceba proteus has begun to be formulated. This does not 

 seem strange, even in view of its common use in laboratories, 

 since the difficulties attendant upon the study of the life cycle 

 of such an elusive form, are numerous. 



The isolated observations upon the various activities of Amceba, 

 the accounts of suppositions appendages, and the descriptions of 

 supposedly new species or varieties, are numerous. The fact 

 that so much observational material upon so many apparently 

 nearly related forms has accumulated, and that so many diverse 

 accounts of the habits of one and the same form have been 

 given, has led some investigators to suspect that perhaps much 

 of this material might be combined to throw light upon the life 

 history of possibly some one or two valid species in whose life 

 cycles some of the forms heretofore described might prove to be 

 merely developmental stages. This suspicion has been strength- 

 ened recently by the fact that some of the Rhizopoda closely 

 allied to the Amceba proteus, whose life cycles are now known, 

 show both widely varying forms and habits during different 

 stages in their growth and reproduction. 



Investigations of the life history of Amceba proteus which have 

 hitherto been made make it possible to generalize, to some 

 extent, upon the course of some of the changes which take place 

 during its development. There seem to be several modes of 

 reproduction in this form, and several intermediate stages be- 

 tween young and adult before the life cycle is completed. In this 

 communication an attempt is made; first, to review briefly 

 what we know of the life history of Amoeba proteus; second, to 



1 Grateful acknowledgment is here made of the aid of Professor H. D. Reed, 

 of the department of zoology, Cornell University. 



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