114 \XATOMY AND PHYSIOLOGY 



liave kept them alive in sea-water and examined their daily 

 habits. They appear to have excited abundant attention 

 in the closet, and but very little in their natural localities. 

 Their ideas are so loose and incleh'nite that it would really 

 be a loss of time to seriously examine and attempt to 

 refute them ; and as Dr. Johnston, in his ' History of 

 British Sponges/ has given in his Introduction, Chapter II, 

 an excellent digest of the various opinions of the previous 

 writers on the subject, I shall content myself with referring 

 my readers to the work of that eminent author for further 

 information on these subjects, and of briefly referring to 

 the few actual observations that appear to have been made 

 by naturalists. 



Marsigli, at the beginning of the eighteenth century, has 

 stated that he had seen contraction and dilatation in the 

 oscula of several sponges just removed from the sea. 



After Marsigli, Ellis (Ellis and Solander), pp. 184, ISO, 

 and 187, (see also ' Zool. Journ.,' pp. 375, 370,) enunciated 

 similar opinions founded on his own observations on the 

 action of the oscula and their currents ; but neither of those 

 authors was aware of the true mode of the entrance of the 

 water into the sponge a much more difficult problem to 

 solve than its exit through the oscula. 



Cavolini, in his researches, although made on sponges 

 recently taken from the sea, failed in seeing the action of 

 the oscula as Ellis had done, and he accordingly disputed 

 their truth. At a later period, Colonel Montagu, although 

 actually examining them in the places of their growth, 

 arrived at similar conclusions to those of Cavolini, and, like 

 that author, he believed them to be animals of a very torpid 

 nature. Montagu's reasoning to prove the animality of 

 sponges is for the most part sound and excellent ; he says : 

 " Whether motion has ever been discovered or not in any 

 species of sponge, is not, I conceive, of so much importance 

 as some naturalists would appear to consider. Those who 

 are solicitous in their inquiries after the animals which they 

 have supposed to construct the vesicular fabric of sponges, 

 have expressed their surprise that in this age of cultivated 

 science no one should have discovered them, must have 



