4 M. E. Hiickel on the ih-ijanizatiou of Sponges, 



the minuto striK'turo ot" tlio sjxingcs has Ik-cu made known of 

 late by the researehes of Lieberkiihn and Kiilliker, the more 

 did this isohited position of the ehiss of sponges with its spe- 

 cific " water-vascular system " appear to be established. 



In opposition to this ])redonHnant conce])tion, only a few 

 iiatnralists have of late adhered to the older ojjinion, that the 

 ypon^ia' were of all animals most nearly allied to the corals. 

 Among these few Leuekart is especially to be noted. In 1854 

 he directly asserted the relationshij) of the sponges and ])olypes 

 (corals) in the following words : — " If wc imagine a polype- 

 colony wuth imperfectly separated individuals, without tenta- 

 cles, stomachal sac, and internal septa, we have in fact the 

 image of a s])onge with its large '■ water-canals ' opening out- 

 wardly." Leuekart accordingly })laeed the sponges in the 

 system with the corals, in the natural })rimary grou}) of the 

 Coeleuterata, the typical arrangement of the organization of 

 which he had been the first to recognize, in 1848, in their 

 gastrovascular apparatus, the " coelenteric canal-system." He 

 did not, however, either then or afterwards, adduce any fur- 

 ther proof of the near relationship of the sponges and corals, 

 or demonstrate in detail the homologies actually existing be- 

 tween the two classes. 



When I was staying, for three months, in the winter of 

 18G6-G7, upon the Canarian island of Lanzarote, I induced 

 my travelling companion and pu})il, M. Miklucho-Maclay, of 

 St. Petersburg, to investigate thoroughly the extraordinarily 

 rich sponge-fauna which we met with upon the lava-blocks of 

 Puerto del Arrecife, the harbour of the island. The most 

 important result of these spongiological investigations, of the 

 correctness of which I have repeatedly convinced myself by 

 my ow^n observations, was the fact that the sponges stand in 

 a much nearer relationship to the corals than has been pre- 

 viously admitted, and even than Leuekart had supposed. In 

 particular, it appeared, from Miklueho's investigations, that 

 the " perfectly peculiar " canal-system of the sponge-body was 

 by no means such a jjceuliarly specific arrangement, but rather 

 equivalent in general, both in form and function, to the gastro- 

 vascular system or ccelenteric apparatus of the Cadenterata, 

 and especially of the corals ; in fact that this " nutritive sys- 

 tem " is both homologous and analogous in the two classes. 

 I was able the more impartially to recognize this highly im- 

 portant fact, by wliich tiie tnie affinity of the Spongiai and 

 Ccelenterata is definitively established, because ])reviously, 

 following the prevailing opinion, and supported particularly 

 upon the views of Lieberkiihn and Oscar Schmidt, 1 had re- 

 garded the sponges as peculiar Protozoa, most nearly allied to 



