162 Dr. G. C. Wallich on the Type 



(nor has this ever been my opinion), but only that these dif- 

 ferences are neither commensurate in importance, nor at all sujffi- 

 cientin kind, or sufficiently constant, to be admissible as proofs of 

 such advance. And this will be seen from the following short 

 extract from my observations on the Polycystina, taken from 

 the '■ Quarterly Journal of Microscopical Science ' for July 

 1865 : — " Although not prepared to regard the degrees of 

 differentiation (as described by Dr. Carpenter) as applicable 

 to the demarcation of orders, or as affording perfectly constant 

 characters under any circumstances^ there cannot be a doubt 

 as to their affording, in the majority of cases, a valuable means 

 of completing generic diagnosis. Beyond this their value does 

 not appear to extend." 



The only point which might reasonably be deemed open to 

 discussion (though probably not by any one who has witnessed 

 the behaviour of the body-substance of Actinophrys sol when 

 being torn to bits and devoured piecemeal by an Amoeba) is 

 that alluded to when Dr. Carpenter says that " a particle of 

 protoplasm detached from the general mass of the body of a 

 Ehizopod will put forth the pseudopodia cliaracteristic of its 

 type,"' — Arcella being specified as putting forth the " lobose " 

 pseudopodia of Amoeba^ and Polystomella (itself a Forami- 

 nifer !) being, curiously enough, singled out as putting forth 

 the " delicate thread-like " pseudopodia of — the Foramini- 

 fera *. 



As interpreted by me, the appearances here described, 

 although not indicative of sufficiently important or constant 

 " differences " in the constitution of the exterior layer and 

 interior protoplasmic mass to be available as ordinal di- 

 stinctions, prove in a very decisive manner that there cannot 

 be any thing approaching to a definite external layer f ; 

 unless we are also prepared to believe, because an oil-globule 

 retains its form whilst suspended in pure water, or, if split up 



* Those who have studied the living Foraminifera, and know to their 

 coat how much time and patience is necessary in getting these intensely 

 sensitive beings to project their pseudopodia at all, will, I think, agi-ee 

 with me that there is more conveyed in Dr. Cai-penter's statement on 

 this point than could possibly have been intended by him. For two 

 whole years the naturalists on board the * Challenger ' watched constantly 

 and anxiously before their eyes were rewarded with a sight of the pro- 

 j ected "pseudopodia of the ubiquitous Foraminifera of the open ocean. 

 He must have been an exceptionally fortunate observer, therefore, who 

 saw the crushed " particle " of the complex-shelled Polydomella put 

 forth the pseudopodia of its tribe. 



+ Of com'se I except what is observable when the final stage of the 

 life-cycle of Atiiceba has arrived, namely its encystment, as having no 

 real bearing on the present question. 



