682 



SCIENCE 



[N. S^ Vol. XLII. No. 1089 



work of fibrils, but examination of the clot under 

 the ultra-microseope demonstrates that it is de- 

 posited as a meshwork of needles or crystals, which 

 are formed separately and subsequently cohere 

 to make a firm gel. The traditional fibrin net- 

 work must be considered as an artefact produced 

 by mechanical stress. In diluted plasmas or in 

 solutions of fibrinogen made to clot by the addi- 

 tion of thrombin, the process of formation of the 

 needles can be followed to a certain extent. They 

 develop by the aggregation of amicrons to form 

 visible particles which assume quickly the shape of 

 short rods. These latter may exhibit at first very 

 active movements, more abrupt and extensive than 

 the ordinary Brownian movements. The minute 

 rods lengthen into needles presumably by accretion, 

 although the actual process can not be followed. 

 The retraction of the clot is one of its characteris- 

 tic properties and must be referred to a slow con- 

 densation of the needles due to a closer aggrega- 

 tion of the particles. A moderate concentration 

 in hydroxyl-ions in the fibrinogen solutions or 

 plasmas increases the degrees of dispersion of the 

 colloidal particles, and in this condition the addi- 

 tion of thrombin causes the formation of a gel of 

 an entirely different character. This gel is non- 

 retractile and under the ultra-microseope reveals 

 no visible structure. Neutralization or slight 

 acidification, insufficient to precipitate the fibrin- 

 ogen, restores the property of giving fibrin- 

 needles by interaction with thrombin. With the 

 exception of the gels of the sodium salts of the 

 fatty acids described by Zsigmondy, fibrin is the 

 only gel formed by an emulsion colloid which ex- 

 hibits clearly a vectorial or crystalline structure. 

 As far as the observations have been carried, this 

 peculiar characteristic is exhibited by the blood 

 of all the vertebrates. In the blood of inverte- 

 brates (erustacea), a different gel is formed in 

 clotting. 



Origin, of the Flight of Birds: C. "William Beebe. 

 (Introduced by Henry Fairfield Osborn.) 

 Mr. Beebe has discovered both in the young of 

 living birds and in Archceopteryx a series of pow- 

 erful flight feathers on the hind limb, which he 

 will demonstrate in support of a new theory of 

 the origin of the flight of birds. 



Ornithological Survey of the Andes and Western 



Coast of South America: Frank M. Chapman. 



(Introduced by Henry Fairpield Osborn.) 



The ornithological survey of the west coast of 



South America and of the Andes is now in its 



fourth year. It is organized along the lines which 



the United States Biological Survey has intro- 



duced in this country. Dr. Chapman will present 

 a resume of the methods of exploration of the 

 area already covered and of the principal results 

 attained in regard to the origin and geographic 

 distribution of the bird life of western South 

 America. 



The Archegonium and Sporophyte of Treubia in- 

 signis Goeiel: Douglas Houghton Campbell. 

 (To be read by Professor Coulter.) 

 Treuiia is a remarkably large liverwort discov- 

 ered by Goebel in western Java. It has since been 

 found in several widely separated regions. The 

 writer discovered it on Mt. Banajao, Luzon, the 

 only station yet reported for the Philippines. The 

 material for the present paper was collected by 

 the writer at the original station, Tjibodas, in 

 western Java, in 1906. The archegonium differs 

 from that of other liverworts in the increased 

 number of rows of peripheral cells in the neck, 

 there being always more than six. The young 

 embryo has a large haustorium, much like that 

 found in Podomitrium or Pallaircinia. The foot 

 is not clearly delimited, and the differentiation of 

 the sporogenous tissue takes place at a later 

 period than is usual. No elaterophore is present, 

 and no definite relation of spore mother-cells and 

 elaters can be detected. The elaters finally be- 

 come very long. A very massive calyptra is de- 

 veloped. The ripe capsule is ovoid in form, and 

 opens by four somewhat irregular valves. Treuiia 

 probably is the nearest to the typical leafy liver- 

 worts (Aerogynce) , of any anacrogynous liverwort. 



Fossil Calcareous Algce from the Panama Canal 

 Zone, with Seference to Beef-iuilding Alga: 

 Marshall A. Howe. (Introduced by N. L. 

 Britton.) 



After referring to the recent marked develop- 

 ment of interest in the fossil calcareous algse and 

 the increasing recognition of their importance in 

 the formation of limestones, the speaker will dis- 

 cuss in some detail certain Lithothamniese, col- 

 lected in Pleistocene and Oligocene strata of the 

 Panama Canal Zone by T. Wayland Vaughan and 

 D. F. MacDonald, of the United States Geological 

 Survey. Lantern slides will be shown illustrating 

 the habit and microscopic structure of three spe- 

 cies which are to be described as new. One of 

 these, from the Pleistocene flats near Mt. Hope, the 

 speaker considers to be represented also by living 

 specimens found by him in the Colon region, only 

 a few kilometers distant. The other two, from the 

 Oligocene, perhaps find their nearest relatives in 

 certain fossils from the Tertiary of Austria. 



