440 



SCIENCE 



[N. S. Vol. XXXI. No. 794 



five widely different kinds of animals. In each 

 animal the most painstaking care was taken to 

 make certain that all motor or sensory or both 

 of these cells, innervating a given organ had been 

 completely destroyed. In spite of the total re- 

 moval of the nerve stimuli the missing organ was 

 regenerated in every case. Thus the frog tadpole 

 regenerated its tail, the adult newt D. viridescens 

 regenerated its tail and leg, the earthworm its 

 head, the starfish its arm, and the planarian 

 D. lacteum the anterior third of its body. It was 

 pointed out that the agreement among these very 

 different organisms probably signified that ani- 

 mals as a whole, whether during their larval or 

 during their adult stage of development, regen- 

 erate their missing organs independently of a 

 central nerve stimulus. 



At the annual dinner and business meeting of 

 the New York Academy of Sciences, held at the 

 Hotel Endicott, New York City, December 20, 

 1909, the following officers were elected for the 

 Section of Biology for 1910: 



Chairman — Professor Charles B. Davenport. 

 !/ — Dr. L. Hussakof. 



A EEGULAB meeting of this section was held at 

 the American Museum of Natural History, Jan- 

 uary 10, 1910. In the absence of Chairman Chas. 

 B. Davenport, Mr. Roy W. Miner presided. The 

 following papers were read: 

 Some Remarks on Myriapods : Mr. KoY W. Miner. 



The speaker gave an illustrated talk on the 

 myriapods, dwelling on their classification, evolu- 

 tion and morphology. Handlirsch's theory of the 

 derivation of the Crustacea, Myriapoda and Hexa- 

 poda from pro-annelidan stock through trilobite 

 forms was discussed in some detail, special atten- 

 tion being given to the evolution of the ancestral 

 insects (Palcodictyoptera) from the trilobites, 

 and their relation to the primitive myriapod 

 stock. All the more typical myriapods were illus- 

 trated and their striking anatomical features 

 commented on. 

 The Vltra-microscope and its Application to the 



Study of Microscopically Invisible Particles: 



Dr. Max Mobse. 



The ultra-microscope was devised by Zslgmondy 

 and Siedentopf on the principle determined by 

 Tyndall, that if a solution is examined under the 

 microscope by means of horizontal illumination 

 and not by light transmitted through it by the 

 substage mirror, the particles within the solution 

 polarize the light and thereby render them visible 



as scintillations against a dark background. By 

 means of this instrument, solutions which appear 

 perfectly homogeneous by means of the ordinary 

 microscope are shown to be composed of particles 

 in suspension. Bodies approaching the dimensions 

 of molecules can be made visible. 



Colloidal solutions have been analyzed by means 

 of the ultra-microscope and shown to be suspen- 

 sions of particles in a homogeneous medium. 

 Thus, colloidal gold and platinum are resolved 

 into such psewrfo-solutions. Albumens fall under 

 this heading and studies of their nature have 

 shown that they are not homogeneous in solution, 

 but are rather fine suspensions. 



The ultra-microscope as first devised has been 

 modified so as to be adapted to the study of 

 living bacteria.- The substage condenser of a 

 microscope is replaced by one where the lens, in 

 place of being biconvex, is parabolic and a stop is 

 placed in the center of the disc so that no direct 

 rays pass to the eye, but only those that have 

 been polarized by the bacteria which receive the 

 rays that are sent through them horizontally. 

 The bacteria flora of teeth was shown. Spiro- 

 ciifetes and rod forms are seen and tneir locomotor 

 organs are made visible. 



Notes on the Restorations of the Cretaceous Birds 



Hesperornis and Baptornis: Mr. Babnum 



Bbown. 



A few brief notes from a forthcoming paper 

 were presented. The anatomy of Hesperornis as 

 known from described material was discussed and 

 compared with a skeleton recently mounted in the 

 American Museum. In this specimen for the first 

 time a complete tail is known. The swimming 

 pose here chosen is accepted as the one that best 

 represents the aquatic habits of the bird and more 

 nearly conforms to the structure of the limbs. 

 The peculiar arrangements of the palate bones in 

 Hesperornis and the contemporaiy Baptornis were 

 shown to constitute characters that distinguish 

 them fixjm all known birds. 



Two new specimens have made possible a paper 

 restoration of Baptornis which in some characters 

 is more primitive than Hesperornis. The striking 

 features are a complete fibula, heretofore known 

 only in Archwopteryx and a very long tail of 

 which fourteen vertebrae are preserved. There 

 were at least sixteen. The palate bones are like 

 those of Hesperornis. 



L. Hussakof, 



Secretary 



Amebican Museum of 

 Natueal Histoey 



