May 24, 1907] 



SCIENCE 



821 



teratology for the elucidation of ptylogenetic 

 morphological problems. This purpose is set 

 forth in the paragraph -which concludes a 

 preface to the Beitrage in which Braus dwells 

 on the distinctions between the historico- 

 genetic and the dynamic aspects of biological 

 problems. " The close relations," he says, " of 

 this branch of experimental embryology to the 

 program of ' Gegenbaur's Morphologisches 

 Jahrbuch' led me, by agreement with the 

 editor and publisher of this journal, to em- 

 body my ' Experimentelle Beitrage zur Mor- 

 phologie' in it and thus to certify their ap- 

 purtenance to the life work of the founder of 

 modern morphology. On the other hand, in 

 order to emphasize the unity of purpose of th« 

 ' Experimentelle Beitrage ' and to make them 

 more readily accessible to those who care espe- 

 cially for the broad aspects of experimental 

 embryology and for its relations to the physi- 

 ology of development, the Beitrage following 

 their appearance in the Jahrbuch are to 

 brought out in the form of separate Hefte. 

 It is anticipated that several Hefte can be 

 bound into a volume. Should they grow in 

 general into a collection for experimental- 

 embryological work which has the historic- 

 morphological problem as its aim, yet in which 

 sight is never lost of the relations of the facts 

 discovered to the other aspect of biological 

 investigation, that of the physiology of devel- 

 opment, there may be added other volumes to 

 the series and the progress here aimed at may 

 prove lasting." 



Thus far two Hefte have appeared. These 

 Contain reprints from the Morphologisches 

 Jahrbuch of articles on experimental embry- 

 ology and teratology by Braus and one of his 

 pupils. Bd. I., Heft 1, is given up to the 

 preface above mentioned, and to a paper en- 

 titled '1st die Bildung des Skeletes von den 

 Muskelanlagen abhangig.' A series of experi- 

 ments on the developing pectoral fin of sharks 

 leads Braus to conclude that in the selachian 

 fin the skeleton develops independently of the 

 musculature but that parts of the skeleton are 

 dependent upon other parts for stimulus to 

 development. 



In Bd. I., Heft 2, there is an article by O. 

 Bender entitled ' Zur Kenntnis der Hypermelie 



beim Froseh.' This gives a description of the 

 external form and of the skeletal muscles and 

 nerves of a left supernumerary hind leg of a 

 frog. Deductions are drawn as to the prob- 

 able cause of the anomaly. 



The chief paper in this Heft is one by 

 Braus on the ' Vordere Extremitat und Oper- 

 culum bei Bombinatorlarven ' in which Braus 

 shows that although normally the fore limb at 

 a certain stage of development appears to 

 break through the operculum yet, if no fore- 

 leg is developed, there is none the less an 

 aperture formed as if the leg were present. 

 The developing limb has the power to force its 

 way through a covering of skin artificially 

 formed above it. The results of the experi- 

 ments are considered from the point of view 

 of phylogenetic morphology. 



All anatomists acknowledge the great help 

 which the study of normal embryology has 

 been in the development of a science of struc- 

 tural form. That accidental and experiment- 

 ally produced abnormality of structure may 

 help to clear up obscure fields of anatomy has 

 been abundantly proved of late years. Ab- 

 normalities and variation in the structure of 

 man and some other animals have long been 

 used as a basis for phylogenetic speculation. 

 It is not improbable that teratology controlled 

 through experiment may throw interesting^ 

 light on this aspect of biology. We trust that 

 the ' Beitrage ' may serve to stimulate more- 

 work in experimental embryology in its mor- 

 phological aspects. On the other hand, it is- 

 to be hoped that vague speculation will not 

 take up an undue amount of the pages de- 

 voted to the subject. C. R. B. 



Bhythmical Pulsations in Scyphomedusm. By 

 Alfred G. Mayer, Director of Department 

 of Marine Biology of the Carnegie Institu- 

 tion of Washington, Tortugas, Florida. 

 Pp. 62, with 2 plates and 36 text figures^ 

 Washington, D. 0. The Carnegie Institu- 

 tion. 1906. 



Among the wealth of new material for in- 

 vestigation which the Carnegie Station at 

 Tortugas has placed at the disposal of the sci- 

 entific public Dr. Mayer has discovered that a 

 small seyphomedusse, Cassiopea xamachana^ 



