Reproductive Phenomena of the Amoeban Rhizopods. 335 



have clearly established this fact. My object in dwelling on the 

 observations now recorded is to show how inseparably most of 

 the minor distinctions are connected with accidental changes of 

 physical conditions, and how guarded we should be in assigning 

 limits to variation before we have become acquainted with the 

 extent to which such changes may operate. 



In my previous papers it was stated that many incidental facts 

 led me to believe in the narrow limitation of species in Amoeba, 

 if not in their absolute unity. The appearances presented by 

 the specimens now under notice have served to confirm that 

 belief, and I can hardly imagine it possible that any person, 

 viewing them unbiasedly and witnessing the occurrence of ex- 

 treme variability even in the earliest stage of the Amoeba, when 

 (as seen by me within the past few days) countless numbers of 

 these minute organisms alternately assume the characters of 

 the most " lobose '' type and of Actinophrys, could arrive at any 

 other conclusion. 



But the history of these Amoeba is not left in doubt ; for not 

 only did a fresh supply of confervoid material, scraped ofi" and 

 delivered to me as procured, present specimens after being im- 

 mersed in water for a few days, but (in order to exclude those 

 sources of error that might be supposed to attach to my observa- 

 tions had the supply been obtained from my own garden, where 

 the refuse of aquaria is at times flung out) a portion of confer- 

 void growth taken from another locality*, having been consigned 

 to water for a few days, was found to furnish similar results. 

 Lastly, with a view to put the matter to a still more severe test, 

 a small quantity of the material first obtained from Mr. Tom- 

 kins was placed on a plate of glass and left to dry completely 

 by evaporation. In three days it was again covered with water. 

 Twenty-four hours afterwards no traces of life beyond a few 

 young Chilodontes and monads were visible. In forty-eight hours 

 Amoeba were observed, although in much smaller number and 

 more sluggish in their movements than was the case prior to 

 this second desiccation ; whilst after the lapse of four days the 

 Amoeba, although still less numerous, were as active as ever. 



In the confervoid material recently obtained I detected nume- 

 rous effete cijsts of Amoeba, some quite empty and crumpled up 

 into angular folds, some enclosing the empty frustules of a 

 diatom that occurs abundantly in a living condition in the damp 

 soil associated with the confervoid layer — namely, Nitzschia 

 Amphioxj/s; whilst others enclosed sarcoblasts, and in some 

 examples coarsely granular nuclear bodies which I at once 



* The spot selected was a gravel walk, at one part of which rain had 

 lodged occasionally. It had, to my knowledge, heen repeatedly raked 

 over during the past three months. 



