410 ANNALS NEW YORK ACADEMY OF SCIENCES 



dition may be understood only if we consider the individual a mere carrier 

 and protector of the germ. In the evolution of species not the characters 

 of the fittest individual are selected and transmitted to the descendant 

 but those of the fittest to preserve the progeny. 



The paper was illustrated with specimens and lantern slides. 



Miss Wood said in abstract : The ornament of Potamidopsis tricarina- 

 tum begins as two continuous spirals, passes through a stage with two 

 rows of nodes and interpolates a third row of nodes in the adult. Potami- 

 dopsis trochleare has three rows of nodes in the young, later loses the 

 median row and has in the adult two continuous spirals. This suggests 

 reversion in the latter species, but in P. tricarinatum, the upper spiral 

 disappears before the introduction of the subsutural and median rows of 

 nodes, while in P. trochleare, the upper continuous spiral of the adult is 

 developed from the subsutural nodes ; hence the two spirals of the adult 

 are not equivalent to the two spirals of the young P. tricarinatum. P. 

 trochleare illustrates progressive development resulting in simplification 

 of structures. 



Miss Wood's paper was illustrated with specimens and diagrams. 



Mr. Matausch gave an account of the successive stages in the construc- 

 tion of an anatomical model of a spider for museum exhibition. He ex- 

 hibited a number of dissected specimens of Lycosa, upon which the model 

 is based, as well as a series of wax models which are made preliminary to 

 casting the final model. 



The Section then adjourned. 



L. HUSSAKOP, 



Secretary. 



SECTION OF ASTRONOMY, PHYSICS AND CHEMISTRY. 



March 21, 1910. 



Section met at 8:15 p. m., Vice-President Campbell presiding. 



The minutes of the last meeting of the Section were read and approved. 



The following programme was offered : 



William Campbell, Notes on the Structure of Wrought Iron. 



Summary of Paper. 



Professor Campbell, in the first part of his paper, dealt with the vari- 

 ous methods of manufacture: (1) The charcoal, hearth processes; (2) 

 Puddling; (3) Rolling of piled or bushelled scrap. Next, the various 

 uses of wrought iron were discussed and the names and trade-marks of 



