Large Crown 8vo.

Cloth.
7s.6d.net (by post, 2s.

3d.).

_Revised Edition._ "Dr.Herbert's hook can be recommended as a trustworthy 'first aid' in the study of a difficult subject.

His style is lucid and concise, and he has provided a glossary which will be of service to many."-- _Athenaeum._ "We have only praise for the result."-- _Eugenics Review._ "Dr.Herbert will be found a safe guide.