Februaky 5, 1904.] 



SCIENCE. 



215 



lines of work. If we suppose four males, 

 having conditions of the character in ques- 

 tion, Avhich we may represent as ah, ef, ij 

 and nm, borne by their germ cells, to mate 

 with four females bearing this character in 

 the conditions cd, gh, kl and op; and if 

 we mate their successive generations, we 

 shall always get the old Galtonian formula. 

 If, however, we suppose the conditions of 

 the character, which we have represented 

 by various letters as borne by the males, 

 to be indistinguishable inter se, so that we 

 may represent them all by x ; and, likewise, 

 those of the female by y; and if we then 

 go through the same hypothetical mating 

 as above, we get the Mendelian formula. 

 It would be dangerous to insist upon a 

 strict adherence to 'purity of the germ.' 

 External and internal factors undoubtedly 

 influence it. It is also improbable that a 

 case could be found in which, by careful 

 work, gradations of the character in ques- 

 tion could not be found. "We would, there- 

 fore, conclude that the Mendelian school 

 arose either by an unfortunate selection of 

 data (taking something in which the varia- 

 tions of the character were hard to per- 

 ceive and measure), or by a careless hand- 

 ling of the data used. 



Evolution without Mutation: C. B. Daven- 

 port, University of Chicago. 

 While recognizing that mutation is an 

 important factor in evolution, the author 

 finds, from a statistical study of geograph- 

 ical and paleontological series, that the 

 transitions between species of the scallop 

 (Pecten) may be graduated, and of the 

 order of individual variations. Thus the 

 Pectens from Cape Hatteras are inter- 

 mediate in their qualities between those 

 from Cold Spring Harbor, Long Island, 

 and Tampa, Florida. 



Also the fossil Pecten ehonus of the 

 Pliocene Nansemond River (Virginia) beds 

 taken from the lowest to the highest beds 



leads in a uniform series toAvards the recent 

 P. irraclians of North Carolina. 



'^Studies in Compensatory Regulation: 

 Chaeles Zeleny, University of Chicago. 

 The ontogenetic development of the 

 opercula in the serpulid Hydroides corre- 

 sponds very closely with the probable 

 phylogenetic development. The regener- 

 ation, however, does not agree with the 

 ontogeny. In both ontogeny and regener- 

 ation there is a close correlation between 

 the two opercula, and each side has the 

 potentiality of forming a functional oper- 

 culum. When one side has a lead in de- 

 velopment at the start it restricts the other 

 to a rudimentary condition. Wlien both 

 have an equal start two functional opercula 

 develop. A similar close relation between 

 organs is shown in other cases. In the 

 serpulid Apomatus after removal of the 

 branchiEE and opercula, the differentiation 

 of the new opercula is much more rapid 

 when the posterior region of the body is 

 also cut off than when this region is un- 

 injured. In the decapod crustaceans 

 Gelasimus and Alpheus, when both chelas 

 are thrown off the animals pass through 

 the succeeding molts sooner than when no 

 chelas, or only one, is removed. Finally, in 

 the ophiurid Ophioglypha, the rate of re- 

 generation of the arms is greater the 

 greater the number of removed arms, with 

 the exception of the case where all are re- 

 moved. 



Iridescent Feathers: R. M. Strong, Chi- 

 cago, 111. 



*Study of Cross-sectional Courses through 

 the Brain with Cortex Surface Relations 

 hy Aid of Fuller Sections and Models: 

 Charles H. Hughes, St. Louis. (Read 

 by title.) To be published in The 

 Alienist and Neurologist. 



The Morphology of the Vertebrate Head 

 from the View-point of the Functional 



