GENERATION OF ANIMALS, III. xi. 



this manner is plain in the case of bees and insects 

 of that sort, as their lower part is large to start with 

 and the upper part smaller. The arrangements for 

 growth in the Testacea are on the same lines. This 

 is shown in the convolutions of the spiral-shelled 

 creatures, which as thev grow always become larger 

 towards the front and the " head " as it is called. 



This practically completes our description of the 

 manner of generation of these animals and of the 

 others that are generated spontaneously. 



The fact that all " the Testacea take shape spon- Examples of 

 taneously is shown by considerations like the follow- spontaneous 

 ing : They form on the side of boats when the frothy ° 

 slime * putrefies ; and also, in many places where 

 nothing of the kind had been present pre\'iously, 

 after a time when the place has become muddy 

 owing to lack of water, "^ lagoon-oysters,'' as they are 

 called, a kind of testaceous animal, have been formed ; 

 for example, on an occasion when a naval squadron 

 cast anchor off Rhodes, some earthenware pots were 

 thrown out into the sea, and as time went on and 

 mud had collected round them, oysters were con- 

 tinually found inside them. Here is a piece of 

 evidence to show that animals of this kind emit no 

 generative substance : people from Chios transported 

 some live oysters across from Pyrrha in Lesbos,' 



** Cf. H.A. 547 b 11. Apparently barnacles, which are, 

 however, Crustacea, not Testacea. 



' The lagoon at PjTrha seems, as D'Arcy Thompson 

 (prefatory note to translation of H.A.) suggests, to have 

 been one of the chief places where Aristotle carried on his 

 researches. The strait leading to it is mentioned again at 

 P.A. 680 b 1 (a passage where also the " eggs " of sea- 

 urchins and ovsters are discussed), and several times in H.A. 

 Cf. 761 b 4. 



365 



