406 



SCIENCE. 



[N. S. Vol. XIV. No. 350. 



fulness for the vital processes. That we 

 cannot explain certain phenomena exhibited 

 by living organisms on the mechanical or 

 better the physical, hypothesis does not 

 necessarily require the postulafeion of a 

 vital force ; it may rather be due to our 

 ignorance of the physico-chemical and me- 

 chanical factors at work, and the progress of 

 modern investigation has steadily tended 

 towards the elucidation of more and more 

 of the vital phenomena aschemico-physical 

 or mechanical processes. In one of the 

 general sessions of the Congress the same 

 problem was the topic of a lecture by 

 Biitschli, of Heidelberg, whose work on the 

 structure of protoplasm necessarily inclines 

 him towards the mechanical side. The 

 problem, of course, cannot as yet be settled, 

 but the opinion of the majority who took 

 part in the discussion seemed to be in favor 

 of the physical theory, holding that the 

 neo-vitalists had not demonstrated the ex- 

 istence of a special life force or a necessity 

 for such a force. 



One of the most interesting and instruc- 

 tive of the lectures before the entire Con- 

 gress was that given by Professor Poulton, 

 of Oxford, on ' Mimicry and Natural Selec- 

 tion.' His thesis was the defense of Dar- 

 win's theory of mimicry, and in a clear and 

 convincing manner he showed that many of 

 the peculiarities exhibited by mimicking 

 animals can be explained plausibly and 

 satisfactorily on no other hypothesis. His 

 lecture was illustrated by lantern slides, 

 photographed in colors, showing numer- 

 ous cases of mimicry in insects collected, 

 with a special view to the study of this 

 question, in Mashonaland, South Africa. 

 Other lectures in the general sessions were 

 given by Professor Grassi of Rome on ' The 

 Malaria Problem from the Zoological 

 Standpoint '; Professor Delage, of Paris, on 

 ' The Theories of Fertilization ' ; Professor 

 Forel, of Morges, on ' The Psychic Peculi- 

 arities of Ants ' ; Professor Branco, of Berlin. 



on ' The Fossil Remains of Man,' the last 

 named making the rather startling sugges- 

 tion that Pithecanthropus may have been 

 neither man nor ape nor yet a connecting 

 link between the two, but a cross between 

 pliocene man and an ape ! 



Of the papers read before the various 

 sections there were but few which call for 

 special notice. One of the most important 

 was the announcement by Professor Patten 

 that he had been able to detect the exist- 

 ence of a series of three jointed appendages 

 in specimens of Gephalaspis preserved in the 

 British Museum, a fact which, taken along 

 with the structure of the shell and the 

 arrangement of organs which may be iden- 

 tified with median and lateral eyes, seems 

 to indicate a close affinity of these sup- 

 posed fishes with the merostomatous Crus- 

 tacea. In the section for vertebrate anat- 

 omy and embryology, Hubrecht presented 

 the results of his studies of the develop- 

 ment of Tardus, which seem to explain 

 the significance of the belly-stalk of the 

 higher mammals, and Kopsch demon- 

 strated by interesting experiments upon the 

 blastoderm of the chick that Balfour's 

 view that the primitive streak lay entirely 

 posterior to the body of the embryo re- 

 quired considerable modification. Papers 

 were also presented by Schauinsland on 

 the development of the skull of Hatteria 

 and of Gallorhynehus and by Mitrophanow 

 in the early development of the ostrich. 



In the section for experimental zoology 

 in additioQ to the paper by Driesch already 

 mentioned, Herbst contributed an interest- 

 ing communication on the influence of the 

 nervous system on regenerated parts, hav- 

 ing found that the regeneration of the eye- 

 stalk of a crab resulted in the formation of 

 an ant^nnule, provided the optic ganglion 

 had been destroyed by the operation. Other 

 interesting papers presented to this section 

 were by Spemann, of Wiirzburg, on the for- 

 mation of double embryos by constricting 



