and other Indigenous Rhizopods. 443 



they throw out pseudopodial processes so various in outline that, 

 were it legitimate to base specific distinctions on such variations, 

 we might have nearly every form heretofore regarded as spe- 

 cifically distinct by some observers produced from one parent 

 source. Indeed, coupling this fact with others bearing on the 

 same subject, although not prepared to affirm that the whole of 

 the varieties of Amoeba are reducible to a single primary specific 

 type, I candidly confess that the balance of evidence appears to 

 me to point towards such a conclusion, and to indicate that the 

 divergences in form and outward characters may be wholly de- 

 pendent on the local and even temporary conditions of the me- 

 dium in which the young animal happens to make its appear- 

 ance in the world. 



It is one of the most perplexing accompaniments of micro- 

 scopic research, that, in addition to the ordinary difficulties at- 

 tending the study of the reproductive phenomena in organisms 

 which admit of observation by the unaided vision or with the 

 aid of low magnifying powers, the chances are greatly against our 

 having the object under our eye at the exact moment that the 

 phenomena are taking place which we desire to witness. From 

 the extreme rapidity with which they are sometimes completed, 

 compared with analogous processes in the higher orders of 

 being, this result is scarcely surprising, even if we treat lightly 

 the difficulty inseparable from the survey of vital actions on 

 so minute a scale. On the other hand, there is reason to fear 

 that erroneous interpretations have often been put upon micro- 

 scopic phenomena in consequence of a failure on the part of the 

 observer to watch them from their commencement to their 

 termination*. The following instances, which are not the 

 only ones that have presented themselves to my notice during 

 my recent close scrutiny of the indigenous Rhizopods, will prove 

 the truth of this remark. 



Fig. 11 represents an abortive effort at division taking place 

 in a specimen of Amoeba radiosa. It will be seen that nothing 

 could be less conformable with the published descriptions and 

 figures of that form than the individual here portrayed. But 

 nevertheless I can vouch for its being the form which has 

 been so named, not only from the fact of the locality in which 

 it was found containing numerous specimens unmixed with 



* The drying up of the minute portion of water in which living or- 

 ganisms are being submitted to long-continued observation under the 

 microscope may be very successfully obviated by resting the slide, when 

 not actually required, across the mouth of a wine-glass containing water, 

 and carefully placing a strip of fine calico across the thin cover, with its 

 ends hanging down into the fluid in such wise as to allow capillary attrac- 

 tion to do all that is requisite. 



29* 



