rather than over the end, and, as in some cases, the new part may even appear in new tissue that covers the end, &c." The word "regeneration" has therefore in biology "come to mean, in general usage, not only the replacement of a lost part, but also the development of a new whole organism, or even a part of an organism, from a piece of an adult, or of an embryo, or of an egg."
In this book, which will be read with pleasure by all zoologists, there are two prominent features: firstly, a very full and complete exposition of the whole phenomena incidental to regeneration, with which few can, and probably fewer still will, cavil; and secondly, a distinct challenge of the doctrine of "natural selection." This last position in itself is a gain to those who hold with Darwin's original conception, as distinct from the new doctrine of some of his latest exponents. A theory only ceases to be one when the last difficulty is overcome, and, as Dr. Morgan well observes, "The custom of indulging in exaggerated and unverifiable speculation bids fair to dull our appreciation for hypotheses whose chief value lies in the possibility of their verification." As an example of our author's method in this discussion, which is throughout conducted in a fair, logical and courteous manner, we may quote the following sentences:—"All that natural selection pretends to do is to build up the complete power of regeneration by selecting the most successful results in the right direction. In the end this really goes back to the assumption that the tissue in itself has power to regenerate more completely in some individuals than in others. It is just this difference, if it could be shown to exist, that is the scientific problem."
We recently had the pleasure of drawing our readers' attention to a book entitled 'Bird-Watching'; this publication might with equal felicity have been called "Insect-Watching," for both volumes are the result of bionomical observation. The author, estimated by Darwin as "that inimitable observer," is widely known by his 'Souvenirs Entomologiques,' of which there
