242 THE BIOLOGY OF THE SEA-SHORE 



having been emptied into the lips by other tentacles the 

 head was extruded and the sand-grains deposited, mixed 

 with cement, outside and just underneath the stone. A fresh 

 lot of sand-grains was then brought up in the same way and 

 deposited beneath the stone on the other side. The tentacles 

 then released their hold, the stone having been " scientifically 

 supported and securely fixed in position with all the skill 

 of a professional builder." The danger of attributing the 

 term " intelligent " to these complex and very remarkable 

 activities is seen when we reflect that workmanship of an 

 equally wonderful kind is displayed by such lowly forms as 

 the Foraminifera in the construction of their shells. These 

 pick out their materials in exactly the same way as do the 

 tube-worms and put them together in a manner which is 

 even more remarkable. Thus, from an enormously varied 

 mass of material Technitella thompsoni picks out only the 

 plates of an Echinoderm, and specimens of Crithonina 

 ptsum, which are exposed to being bored by parasitic worms, 

 will sometimes protect themselves with a " chevaux-de- 

 frise " of sponge spicules. Heron- Allen (19 15), who has 

 brought to light a number of very striking examples of this 

 kind, sees in them illustrations of " purposive intelligence." 

 In criticising this interpretation, Lankester (191 6) remarks 

 that he finds no great difficulty in conceiving of a mechanism 

 in the protoplasm of the Protozoa which selects and rejects 

 building material, and determines the shape of the structures 

 built, comparable with that mechanism which is assumed to 

 exist in the nervous system of insects and other animals 

 which " automatically " go through wonderfully elaborate 

 series of complicated actions. Darwin and others have attri- 

 buted the building up of these inherited mechanisms to 

 the age-long action of Natural Selection and the survival of 

 those individuals possessing qualities or tricks of life-saving 

 value. Lankester, therefore, disagrees with Heron Allen's 

 opinion that the architectural and selective phenomena 

 exhibited by Foraminifera have no relation to adaptation 

 and tropisms. On the contrary, they are not only closely 

 related to such phenomena, but are of the same nature, 



