A Monograph on the Development of Elasmobranch Fishes

Abstract

MR. BALFOUR has finally completed and issued in the form of an octavo volume the researches on the embryology of the dog-fish and its allies, which he commenced at the now celebrated zoological station of Naples in 1874. His results have been made known from time to time during the progress of his work by a preliminary paper in the Quarterly Journal of Microscopical Science, October, 1874, and by a series of articles in the Journal of Anatomy and Physiology, the latter, indeed, being identical with the successive chapters of the present volume. Looking at the work as a whole, we may heartily congratulate not only Mr. Balfour, but English science, on the very great value of this contribution to knowledge. Mr. Balfour, before entering upon the study of the deveopment of the shark-like fishes, had thoroughly qualified himself for the task by a careful investigation of the development of the common fowl, a subject which, although it had always been and remains the favourite, because the most handy, for the embryologist's study, yet yielded several new and interesting results to Mr. Balfour's examination. The methods which are applicable to the hardening and slicing, staining and clarifying of the embryo chick are precisely those which it is necessary to employ in the investigation of the very similar egg of the Elasmobranchs, and accordingly Mr. Balfour had well trained himself for the latter task. The prominent position in Vertebrate morphology which had been assigned to the group of Elasmobranch fishes, through the researches of Gegenbaur, rendered a minute examination of their developmental history urgent. It had become clear that we have in these fishes the nearest living representatives of the common ancestors of the great group of Gnathostomous Craniate Vertebrata, and it was to be expected that a full knowledge of their ontogeny or individual development would carry us yet further back in the line of primitive Vertebrata, and yield a mass of explanatory evidence, exhibiting the development of complex and heterogeneous structures from simpler and more homogeneous forms, likely to serve as a satisfactory starting-point for all Vertebrate morphology.

A Monograph on the Development of Elasmobranch Fishes.

By F. M. Balfour, Fellow and Lecturer of Trinity College, Cambridge. (London: Macmillan and Co., 1878.)