216 AEISTOTLE'S ANAIMA, 



CHAPTER XVI. 



ARISTOTLE'S ANAIMA, OR ANIMALS 

 WITHOUT BLOOD. 



The number of Anaima described or mentioned by 

 Aristotle is about one hundred and twenty, and not less 

 than one-half of these belong to his Entoma. Many of his 

 statements, mostly relating to the anatomy of the Anaima, 

 have been discussed in the preceding chapters. Some of his 

 remaining statements, chiefly about those Anaima which 

 can be fairly well identified, will be discussed next. 



Aristotle gives a description of three kinds of sponges, 

 sufficient to show that they belong to the horny sponges 

 [Ceratosa), including the ordinary sponges of commerce, and 

 he also gives a description of some sponge-like form of life, 

 called Aplysia, because, unlike sponges, it remained black 

 when washed.* One kind of sponge, which he says is 

 compact or close in texture (9ry«voV) and softer than the others, 

 may be the fine Turkey sponge {Euspongia officinalis, var. 

 mollissima) ; another kind, called the sponge of Achilles, 

 very thin, compact, and strong, and commonly laid under 

 helmets and greaves to deaden the effects of blows, may be 

 the lappet variety of Turkey sponge, or, possibly, the brown 

 Turkey or Zimocha sponge {Euspongia zimocca) ; Aristotle's 

 remaining sponge, having a larger base of attachment, and 

 further characterized by being loose in texture ij^avoi) and 

 larger than the other sponges, seems to be the common 

 bath sponge {Hippospongia equina). 



Aristotle says that, on the upper parts of sponges, are 

 hemmed-in passages or ducts (poroi), four or five of which 

 are conspicuous, and that some believed that the food of the 

 sponges entered through these.! 



For two thousand years after Aristotle's time, it was 

 believed that currents of water entered the large passages of 

 a sponge, and it was not until Dr. Grant, after very careful 

 observations, concluded that water was drawn into the 



- H. A. V. c. 14, ss. 2-6. f Ibid. v. c. 14, s. 5. 



