Page:The Zoologist, 4th series, vol 4 (1900).djvu/558

524 years, when this period will be alike termed the Victorian age and the Darwinian era, how will he be associated with this great conception? Was Huxley the Baptist or the Paul to Darwinism? In the light of these volumes we consider him both.

second volume has now appeared of this advanced well-named 'Treatise.' Vol. III., which appeared first, has already been noticed in these pages, and the present volume very fully maintains the excellence of the Oxford publication.

The Editor contributes an introduction on a subject of great biological importance, viz, the cœlom, a name proposed by Haeckel for the cavity in Vertebrate animals often called the "pleuroperitoneal cavity." This is a branch of technical biology of the profoundest interest, but one necessarily little discussed in our bionomic pages. This "introduction" can, however, be consulted as the last word in the investigation to date, and, as its writer has proposed, it is "the vindication of the cœlom as a morphological factor of primary importance in the animal series, and the maintenance of the conclusion that the cœlom by its presence justifies the separation of a higher grade of Enterozoa, the Cœlomocœla, from a lower grade, the Enterocœla, in which it is not differentiated as a separate cavity."

Prof. Minchin has written very fully on the Sponges. These creatures afford their evolutionary evidence, as do all other animals. "Many deep-sea sponges, especially those of the order Monaxonida, are to be regarded as having migrated downwards from the shore-line in comparatively recent times, and in such forms the influence of life in still water is seen in a great regularity of growth, resulting in the development of a secondary symmetry." The colours of Sponges are very varied, and often very bright; but Prof. Minchin states that green is a rare colour among marine Sponges, though it is the usual tint of the freshwater Spongillinæ, where, however, it is due to chlorophyll.