158 NATURE AND AFFINITIES OF THE SPONGES. 



received the confirmation of the many investigators who have subsequently 

 devoted themselves to the study of this special zoologic group, the Metazoic 

 organization and affinities of the sponges, as insisted upon by Haeckel, 

 would undoubtedly have been established upon a firm basis. If, on the 

 other hand, such investigation proved the existence of important errors in 

 the interpretation rendered, neither the intimated affinity of the sponges, 

 nor any of the many side-inferences and deductions connected with and 

 interdependent upon such interpretation, possess further value. As a matter 

 of fact, the crucial test applied has been productive of the most unlooked- 

 for results, for, not only has it been shown that errors do exist, but that 

 these are of such a radical and fundamental nature that the inference is 

 most reluctantly arrived at that Haeckel, carried away in his ardent pursuit 

 of the Metazoic archetype, has lost for the time his power of discrimina- 

 tion between matters of fact and hypothesis, and so evolved from his own 

 inner consciousness those details that are wanting to complete and perfect 

 his theory. This at any rate is the most charitable construction to place 

 on the extraordinary discrepancies found to exist between even the broad 

 structural characteristics of his so-called sponge-gastrula as reported by 

 himself, and as since found to exist in fact by a number of independent 

 witnesses. Without entering now into a precise and extensive account of 

 the data elicited, it will suffice at present to state that on all sides, as 

 demonstrated by the independent investigations of Metschnikoff, Oscar 

 Schmidt, Barrois, F. E. Schulze, H. J. Carter, and the present author, it has 

 been made evident that a reproductive body having the form and organiza- 

 tion of the so-called gastrula or ciliated larva, as attributed by Haeckel 

 to the Spongida, and reproduced in the foregoing woodcut, has no real 

 existence, and that his representation of such a structure is entirely at fault 

 in the following cardinal points. In the first place, this ciliated body never 

 does possess two distinctly marked cellular layers comparable to a true 

 ectoderm and endoderm ; in the second place, there is neither a distinct 

 gastric cavity nor an intercommunicating apical, oral, or other aperture as 

 required for the confirmation of Haeckel's dictum ; while, finally, the anterior 

 and posterior poles have, as compared with what exists in nature, been 

 exactly reversed in order to make them conform with his particular require- 

 ments. This latter circumstance is made obvious from the fact that in all 

 instances, in both his figures and descriptions, the larger cells, which do 

 frequently, but not invariably, occur in connection with these bodies, are 

 stationed by him at the anterior, or his so-called " oral extremity," while 

 in reality they are located at the posterior one. Taken altogether, it is 

 clearly evident that the so-called " sponge-gastrulae," described and figured 

 over and over again in Professor Haeckel's ' Monograph,' are an entire 

 myth, and that the superstructure of the gastraea theory, so far as it rests 

 upon this basis, is entirely worthless. From this it is also clear that a very 

 considerable portion of Professor Haeckel's artistically executed plates in 

 the monograph in question are utterly untrustworthy and worse than use- 



