April 11, 1902.] 



SCIENCE. 



583 



In the earliest stages in which they can 

 be distinguished from body cells they all 

 lie in two little round groups under the 

 blastodermic rim in the posterior part of 

 the embryo, and just at the junction of the 

 three germ layers as well as in the en do- 

 derm itself. 



During the growth of the embryo these 

 clusters move inward from each side to- 

 wards the median line. (Embryo of 3 

 mm.) 



The cells then become separated from 

 each other and are scattered in the unsplit 

 mesoderm, though none are yet to be 

 found in the segmented portion of the 

 middle germ layer. 



When the mesoderm splits, nearly all 

 succeed in getting on the median or 

 splanchnic side of the body cavity which is 

 then formed. 



From this time up to the period of 

 sexual differentiation (embryo of 28 mm.) 

 these cells migrate relatively to the other 

 tissues so that they progressively lie just 

 beneath, at the side of and then dorsal- 

 ward to the intestinal tract. They then 

 make their way through the mesentery in 

 which most of the cells are found (embryos 

 of about 11 mm.), and finally reach their 

 destination in the epithelium of the geni- 

 tal gland. 



During no part of this process are germ- 

 cells ever derived from mesoderm cells, nor 

 do they ever go into the formation of any 

 part of the body. 



They retain their yolk and other char- 

 acteristics of the cells of the early blasto- 

 derm stage and it is the body-cells, not 

 the germ-cells, that are differentiated. 



Thus the hypothesis of Naussbaum that 

 ' sex cells do not come from any cells that 

 have given up their embryonic character 

 or gone into building any part of the body, 

 nor do sexual cells ever go into body for- 

 mation,' finds a confirmation in facts. 



Histological Changes in the Begeneration 

 following Normal Fission of Planaria 

 maculata: W. C. Cuetis. (Read by 

 title only.) 



Variation in the Hepatic Ducts of the Cat: 

 R. H. Johnson. (Read by title only.) 



An Electric Lamp for Microscope Illumin- 

 tion: Maynaed M. Metcalf. (By title.) 

 Will be published in full in Science. 

 M. M. Metcalf, 



Sec7'etary. 



AMERIGATf PHILOSOPHICAL ASSOCIATION. 



The American Philosophical Association 

 held its first meeting at Columbia Univer- 

 sity, New York, on Monday and Tuesday, 

 March 31 and April 1, 1902. The Associa- 

 tion may be regarded as' a daughter of the 

 American Psychological Association, to 

 which fully three fourths of its nearly one 

 hundred charter members also belong. For 

 several years past the Psychological Asso- 

 ciation has provided for the reading of 

 papers in general philosophy at its meet- 

 ings by philosophical sections. This ar- 

 rangement generously met a practical 

 demand, but the relation was anomalous. 

 The desire for more adequate recognition 

 of the philosophical interests was met by 

 the organization of the new Association at 

 a conference held last November in New 

 York. Professor J. E. Creighton (Cor- 

 nell), editor of the Philosophical Eevietv, 

 was chosen president. Professor A. T. 

 Ormond (Princeton), vice-president. Pro- 

 fessor H. N. Gardiner (Smith), secretary- 

 treasurer, and these, together mth Pro- 

 fessors Armstrong (Wesleyan), Duncan 

 (Yale), Everett (Brown) and Hibben 

 (Princeton), were constituted an executive 

 committee to invite others to membership, 

 to draw up a constitution and to arrange 

 for the first meeting. The constitution 

 adopted at the recent meeting defines the 



