NATURE AND AFFINITIES OF THE SPONGES. 159 



less, since, accepting as infallible the representations of so high an authority, 

 these entirely imaginary figures with their accompanying definitions have 

 been already extensively reproduced as proven facts in many recent text- 

 books of biology.* The glaring unreliability of Professor Haeckel's repre- 

 sentations, in this special connection, necessarily justifies more than cus- 

 tomary precaution in accepting as Gospel fact his evidence in other 

 directions, wherever room is left for entertaining the slightest reasonable 

 doubt. A case altogether to the point is afforded by his representations 

 of the spermatozooids of various sponge species, in Plates I, 7, 9, 1 1, 25, and 

 48 of his monograph. Scarcely three years previously, Haeckel, as already 

 stated, declared that sponges were asexual and sporiparous, and that the 

 careful examination by himself of hundreds of specimens had satisfied him 

 that spermatic elements were entirely wanting throughout the class. As 

 pointed out by Mr. Carter, the admission was in itself fatal to his Metazoic 

 or gastraea theory as applied to the sponges, spore production being an 

 essential property of Protozoic organisms only, and the union of true sexual 

 elements, ova and spermatozoa, being of unvarying occurrence throughout 

 all the higher or Metazoic groups. Tacitly, Professor Haeckel evidently 

 acknowledged the trenchant force of Mr. Carter's argument. At any rate it 

 is an interesting and significant fact that so-called true spermatozoa were 

 found ready to hand and produced in abundance in Haeckel's succeeding 

 essay on the affinities of the sponges. The celerity with which these 

 missing elements were discovered in profusion, directly their presence was 

 shown to be essential for the sustenance of his Metazoic theory, and in 

 face of his previously declared incapacity to recognize them after a most 

 exhaustive investigation, when not specially wanted, a few months earlier, 

 is in itself a suspicious circumstance. It is just possible that these sup- 

 posed spermatozoa may represent in some instances a misinterpretation 

 of certain earlier conditions of the ordinary flagellate cells ; but in one 

 special case,t in which the actual fructification of a sponge ovum by sper- 

 matic bodies is delineated, it is difficult to resist the conclusion that the 

 learned professor's fertile imagination as in the case of the gastric cavity, 

 oral aperture, and endodermic cell-layer of his sponge-gastrula has risen 

 to the occasion and kindled into being forms and features possessing no 

 tangible existence. 



Before proceeding to an examination of the evidence towards an 

 elucidation of the precise structure and affinities of the sponges, accu- 

 mulated through other independent sources, one later contribution of 

 Professor Haeckel's demands brief notice. Reference is here made to his 

 separate brochure ' Studien zur Gastraea-theorie,' published in the year 1877. 

 While devoted generally to the exposition of his latest and most matured 

 views upon the gastraea theory, it is specially worthy of notice as the 



* E.g. "Development of Sponge, Ascetta primordialis," in Prof. Huxley's 'Manual of the 

 Invertebrata,' p. 112, fig. vi. 



t 'Monograph of the Calcispongiae,' pi. 48, fig. 6. 



