166 Dr. G. C. Wallich on the Type 



namely the contractile vesicle) — I venture to say that however 

 phviisible Dr. Carpenter's hypothesis may be, it finds no 

 response in natm-e. And I maintain that wc are furnished 

 with the most complete proof that could be desired of the 

 invalidity of the characters derived from the pseudopodia for 

 purposes of ordinal classification, in the passage from Dr. 

 Carpenter's own writings quoted at p. 164. At all events 

 I confess that it is cpiite beyond my humble powers to 

 reconcile the admissions there made on Dr. Carpenter's part 

 with his allegation, already quoted, that " tlie sarcode bodies 

 of his three t3rpes Amoeba, Actinophrys, and Oromia present 

 three distinct stages in the differentiation of the ])rotoplasraic 

 substance of which they are composed," and that " the lines 

 of demarcation thus drawn are as precise as in any other great 

 natural group, between the three aggregations of forms which 

 assemble themselves round the three well-known types " above 

 named. 



But in order to prevent all misconception on this very 

 important question, I must request attention to another ex- 

 tract from Dr. Carpenter's observations on the Systematic 

 Arrangement of the Rhizopods (Nat. Hist. Rev. 1861, p. 461), 

 where he states that " the ordinal designation Reticularia is 

 meant to express the reticulose arrangement of the pseudo- 

 podial extensions, ivhich is its distinguishing character^ 

 And again, at page 463, he says that " the radiating pseu- 

 dopodia of Acanthometra correspond ^^^'ecisely in all their 

 characters with those of Actinophrys, having the same rod- 

 like tapering form, and same regular radiating arrangement, 

 the same mutual isolation, the same slow movement of 

 particles along their surface ; some of them are, however, 

 enclosed in tubular sheaths*, the differentiation of Acantho- 

 metra into ectosarc and endosarc having obviously proceeded 

 further than in Actinophrysr 



But although it is true that in Acanthometra the differentia- 

 tion into ectosarc and endosarc has proceeded further than in 

 Actinojjhrysj it is equally true that it has also proceeded 

 further than in Amoeba. But even stopping short at Dr. 

 Carpenter's point, that it has proceeded further than in 

 Actinophrys, how can this be reconciled with the statement 

 that " the radiating pseudopodia of Acanthometra correspond 



• It was pointed out by me years ago that the appearance of tubularity 

 in Acanthometra is altogether an illusion. There is no such thing as a 

 tubular portion in the structure of these organisms. See a paper " On 

 the Process of Mineral Deposit in the Rhizopods and Sponges, Ann. & 

 Mag. Nat. Hist., Jan. 18G4. 



