4 M, E. Hackel on the Organization of Sjoonges, 



the minute structure of the sponges has been made known of 

 hite by the researches of Lieberklihn and Kolliker, the more 

 did this isoLnted position of the class of sponges with its spe- 

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



In opposition to this predominant conception, only a few 

 naturalists have of late adhered to the older opinion, that the 

 Spongias were of all animals most nearly allied to the corals. 

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

 he directly asserted the relationship of the sponges and polypes 

 (corals) in the following Avords : — " If we imagine a polype- 

 colony with imperfectly separated individuals, without tenta- 

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

 image of a sponge with its large ' water-canals ' opening out- 

 Avardly." Leuckart accordingly placed the sponges in the 

 system with the corals, in the natural primary group of the 

 Coelenterata, the typical arrangement of the organization of 

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

 gastro vascular apparatus, the " coelenteric canal-system." He 

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

 ther proof of the near relationsliip 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 

 1866-67, upon the Canarian island of Lanzarote, I induced 

 my travelling companion and pupil, 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 own 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 Leuckart had supposed. In 

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

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

 by no means such a peculiarly specific arrangement, but rather 

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

 vascular system or coelenteric apparatus of the Coelenterata, 

 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 which the true affinity of the Spongite and 

 Coelenterata is definitively established, because previously, 

 following the prevailing opinion, and supported particularly 

 upon the views of Lieberkiihn and Oscar Schmidt, I liad re- 

 garded the sponges as peculiar Protozoa, most nearly allied to 



