THE current number of the Quarterly Journal of Microscopical Science commences with a memoir, by Dr. G. Thin, on the structure of hyaline cartilage as found by immersing it in a solution of caustic potash at 107° F., and otherwise. A successful potash preparation shows flattened polygonal cells adhering to each other exactly like an epithelium. Much manipulatory experience is necessary for the demonstration of these, and it must be mentioned that the author has “a strong conviction of the uniformity of plan in the general structure of the tissues.”—Mr. Hugh Price writes on a polystomatous condition of the hydranths of Cordylophora lacustris, and figures his specimens. His observations tend to show that the polystomatous condition may be due to injury of the parent hydranth.—Prof. E. R. Lankester, F. R. S., contributes two papers; the first, including further observations on a peach, or red-coloured Bacterium. (Bacteritim rubescens), in which a further account of that organism is given. The second is a valuable account of Prof. Haeckel's recent additions to the Gastræa-theory, illustrated by four important plates exemplifying the letterpress. The following terms are fully explained: Palingeny and Cenogeny, the tendency to recapitulation and to suppress the details of ontogenelic development; Hetero-chrony and Heterotopy, the perturbations in ontogeny as regards time and space. The conceptions with which these terms are associated must be fully mastered by all who study evolution from its developmental aspect. The four chief types of egg-cleavage and of Gastrula-formation are then explained, and the stages which each undergo, the monerula-, cytula-, morula-, blastula-, and gastrula-stages are recounted, the prefixes archi-, amphi-, disco-, and peri- being applied to the four respectively. The nomenclature, though at first apparently formidable, much simplifies this otherwise complex subject.—Mr. C. S. Tomes, in writing on the development of teeth, gives a summary of the many and important results at which he has arrived in his valuable researches, together with the investigations of others which bear on the subject. Goodsir's piimary open dental groove is shown to have no existence. In reality an ingrowth is shown to develop from the deep layer of the epithelium, consisting of a double layer of cells burrowing down into the submucous tisssue, and looking in transverse section like a tubular gland. The next stage consists of an active growth of cells in the deepest end of the epithelial inflection, the immediately subjacent tissue at almost the same time becoming elevated at corresponding points where teeth are to be developed; the subjacent tissue forming a conical papilla, the enamel organ appearing with or even before t.ie papilla. Many important points in the tooth-development of the lizard and fish are also discussed.—Dr. Percival Wright has a note on Stenogramma interrupta, in which the author proves that the tetrasporic fruit of that rare and beautiful Alga was described by Dr. W. H. Harvey, contrary to the assertion of Mr. E. M. Homes.—Mr. W. Bevan Lewis describes the best methods of making preparations of sections of cerebral and cerebellar cortex ior microscopical examination.—Mr. H. C. Sorby, F.R.S., hasapaper on the evolution of Hæmoglobin, based mainly on the fact that the centres of the hæmoglobin bands from the red blood of Planorbis lie two and a half or three millionths of a millimeter nearer the blue end of the spectrum than do those of vertebrate blood.—Reviews of Dr. Klein's “Anatomy of the Lymphatic System,” Part II., and of the English translation of Frey's “Histology and Histochemistry of Man,” are also given, followed by notes, proceedings of societies, &c.