no TOILERS IN THE SEA. 



fixed and plant-like zoophytes, or more robust and 

 fungus-like sponges, as animals. Whether any such 

 persons ever experimented upon a piece of common 

 bath sponge by burning it, and sniffing the odour 

 we are unable to say ; but we should doubt their 

 judgment, or the acuteness of their sense of smell, 

 if they had not at once referred the odour to some- 

 thing akin to burning hair rather than to charred 

 wood. 



We may start with the assumption that sponges 

 are animal, and not vegetable, because, as we pro- 

 ceed, this assumption will be abundantly proved, 

 although the animals may be lower in rank, and 

 even more simple than the zoophytes, and their indi- 

 viduality less easily demonstrated. Because they 

 flourish whilst attached to the rock, by means of a 

 sort of disk at the base, in like manner to the sea- 

 weed, proves nothing, for all further resemblance is 

 at an end, there being only an analogy and no 

 affinity between them. 1 It is a common mistake, 

 into which even men with some claim to be con- 

 sidered scientific occasionally fall, to confound 

 analogy with affinity. Things may be very much 

 like each other, in more particulars than one, and 

 yet possess no relationship whatever. How many 



1 For an account of the History of Sponges, from the earliest 

 times, see the introductory chapters to "A History of British 

 Sponges and Lithophytes," by George Johnston, London. 



