Calcispongias in the Animal Kingdom. 245 



I have already shown that the prevailing error as to the 

 near relationship of the Sponges and Protozoa originated for 

 the most part from a false conception of their conditions of in- 

 dividuality. Because the morphontes (morphological elements) 

 of the first order which form the sponge-organism, the flagel- 

 late and amoeboid cells, exhibit a relatively high degree of 

 physiological individuality, and because the jyersonaliti/ of the 

 sponges built up of these (the morphon of the third order) was 

 not recognized, the former have been regarded as the " true 

 individuals" of the sponge. I have already (1869) refuted 

 this error by demonstrating the homology of the sponge-person 

 with the Acaleph-person, and the composition of the wall of 

 its stomachal cavity of two laminge (entoderm and exoderm). 



This demonstration has been repeatedly attacked during the 

 last two years, and indeed especially by Carter, James-Clark, 

 Saville Kent, and Ehlers. The attacks of Carter and of 

 James-Clark, neither of whom has any conception of the 

 essence of the cell-theory, have already been refuted. The 

 attacks of Saville Kent* are incapable of refutation, and in- 

 deed do not need any, simply because the author neither 

 understands the arguments brought forward by me, nor is in 

 general sufficiently acquainted with the structure and develop- 

 ment of the Sponges and Zoophytes. Evidently Saville Kent 

 (of the Geological Department, British Museum) does not 

 possess even the small measure of zoological knowledge which 

 might be expected from a geologist who works at palajontology. 

 He does not even know the difference between homology and 

 analogy, between the morphological and physiological signifi- 

 cance of an organ. He regards the differentiation of such 

 notions as quite superfluous. Comparative anatomy and on- 

 togeny seem not to exist for Saville Kent ; and as my whole 

 demonstration rests upon the basis of the latter, of course he 

 cannot comprehend it. Ray Lankester has taken the thankless 

 trouble to attempt to communicate to this geologist some of 

 the elementary pieces of preliminary knowledge which are 

 necessary for the discussion of such questions of comparative 



to the nature of Sponges), and in a recently publislied memoir by Pageii- 

 stecher, " Zur Keuntniss der Scliwiimme " (Verhandl. der naturliist.Vereins 

 zu Heidelberg, 1872) ; see also my memou- on the organization of the 

 Sponges &c. ( 18G9, Jenaische Zeitschr. Bd. v. p. .307 ; transl. in Ann. & 

 Mag. Nat. Hist. 4tli ser. vol. v. p]^i. 1 & 107). The later spougiologists, 

 especially Bowerbank, Carter, Lieberkiihn, (). Schmidt, and Kollikor, 

 almost unanimously refer the sponges to a place among the Protozoa, 

 where they are appended sometimes to the Ama3bce, sometimes to the 

 lihizopoda, and sometimes to the Magellata. 

 * Ann. & Mag. Nat. Hist. 1870, 4th ser. vol. v. pp. 201-218. 



