MANY unfamiliar terms, especially the rarer ones, are defined with the help of other technical terms, perhaps equally un- familiar. 

This annoying trick of dictionary-makers could only be avoided by giving a complete account of a large part of biology under each heading, which is impracticable. 

There is nothing for it but to follow up the terms until you come to an entirely intelligible definition. 

Every biological technical term used in a definition is, we believe, itself defined elsewhere in the dictionary; though some semi-technical terms, which can be found in any English Dictionary (such as the Pocket Oxford), are omitted.

We put the letters (q.v.) after a term which is defined else- where only when its definition adds important information to the subject under discussion. It is not put after every term defined elsewhere. The letters cf. are intended to point out a contrasting term.

(Bot.) or (Zool.) before a definition means that what follows applies only to plants or to animals respectively. It is not used where the limitation is obvious.

(Adj.) means that the term defined is an adjective, when this is not clear from the definition.

If a word is not defined in the dictionary, try Uvarov's Dictionary of Science (Penguin Reference Book RI); and consult it for supplementary information on any chemical term.