288 \V. ARCHEtl* 



hence prefer to limit the use of the term to those organisms 

 possessing pseudopodia of a branched " rootlike " character 

 and to apply a name to the whole group more in accordance 

 with them in their totality. Inasmuch as the common 

 bond of union is the undifferentiated protoplasm, they sug- 

 gest the comprehensive name Sarcodina (Sarcode organisms). 

 As there does not exist any proof of a mouophyletic origin 

 of all living beings, but rather a polyphyletic descent must 

 be regarded as more probable, this community of nature 

 cannot be regarded as inherited from a common primitive 

 form, but it is rather to be supposed that under certain 

 similar chemical and mechanical conditions similar forms 

 must have come into existence. Therefore, by the union of a 

 considerable number of these lowest forms as Sarcodina, the 

 authors do not mean to express a community of origin, but 

 rather only that they all have attained to, and remain sta- 

 tionary at, an equally high or, better said, equally low, stage 

 of development. 



Be their origin what they may, one thing continues to 

 force itself on my own mind, and that is the strongly marked 

 specific differences which present themselves in the fresh- 

 water rhizopodous forms, both of inherent characters, habit, 

 behaviour, and idiosyncrasies, but having referred to these in 

 former papers I need not recapitulate.^ I allude, of course, 

 to " fully-grown " examples, in Avhich their characteristic 

 specialities are completely assumed ; no doubt one sees in 

 freshwater collections certain minute heliozoan and other 

 types of a "nondescript" character, which one is compelled 

 to assume, ad interim, may be " young " or undeveloped 

 examples, possibly proceeding from subdivision or from zoo- 

 spores of described species. It is possible, no doubt, that 

 inasmuch as the freshwater forms are vastly more few than 

 the marine, and the lacunae or intervals between the forms 

 wider, and hence standing inter se, more remote, they allow of 

 their mutual differential characters being more readily per- 

 ceived. In Difflugise, &c., the difficulty (as in other groups) 

 is to know if certain forms be amongst those already described, 

 not in seeing the mutual distinctions that present them- 

 selves, and in recognising this or that old friend or stranger 

 (as it may be) when the examples are met Avith, 



Hertwig and Lesser regret their inability to have carried 

 their observations on to the marine forms, and to have sub- 

 mitted the Polythalamia to renewed researches, as bearing 

 on their relation to the Monothalamia. 



As the efforts of the authors were directed to the formation 



* ' Quart. Journal Mic. Science,' n. s., vol. xi, p. 107; vol. xv, p. 129. 



