ON THE USE OF SOME WORDS 9 



has become extended in its meaning to include living struc- 

 tures, such as certain Foraminifera, Sponges, and the coral- 

 line Algae for example, that possess no such organised animal 

 forms as could be, by any possibility, included in the mean- 

 ing of the word polyp. There can be no longer, therefore, 

 any synonymy between the words " Coral " and " Polyp." 



Another word which must be frequently used in a book 

 on Corals is the word " Individual," and this is as difficult 

 or even more difficult to define than any of the others. 

 Many attempts have been made by eminent philosophers, 

 such as Huxley, Bergson, and others, to give a scientific 

 definition of it, but each one seems to lead to absurdities 

 or to a use of the word in a sense that it is not used and 

 cannot be used in common language. To give just two 

 examples to illustrate my meaning. If we were to accept 

 Huxley's definition of the word individual as " the total 

 product of a fertilised ovum," we must regard the winged 

 insect, the Aphis, which we find on our rose trees, not as an 

 individual but as the millionth (or more) part of an individual. 

 Or if we follow Bergson's analysis of the word, then we are 

 led to the conclusion that the Yucca plant and the Pronuba 

 moth, which are known to be mutually dependent on each 

 other for continued existence, are not two individuals but 

 one individual of the fifth or sixth order of individuality. 



In my opinion the only definition of the word that can 

 bring it into agreement .with its usage in modern language 

 in biology is one which expresses the discontinuity of an 

 organism in time and space. 



In the case of an isolated polyp such as a hydra or 

 a sea-anemone, there is no difficulty in grasping the idea 

 of the individual, and, if the hydra is reproducing by 

 gemmation, the bud that is not yet detached from the body 

 wall is a part of the individual hydra. When the bud has 

 developed tentacles, and has lost organic continuity with 

 the parent hydra, it becomes a separate individual. The 

 idea of separate individuality in this case is dependent on 

 the discontinuity in space. 



In the genus Diaseris there is a single free individual 

 polyp which secretes a large fungiform calcareous structure. 



