58 



SCIENCE. 



[N. S. Vol. III. No. 54, 



The scientific program was as follows : 



Friday, Deceniber 27, 1895. 

 C. S. MiNOT : Panplasm. 



B. B. Griffin: The History of the Centrosome in 

 Thalassema. 



B. B. Wilson: Tlie Centrosome in its Relation to 



Fixing and Staining Agents. 

 T. H. Morgan: The Production of Artificial Areho- 

 plasmic Centers. 



F. K. Lillie: On the Smallest Parts of Stentor Capable 



of Regeneration. 

 E. G. Conklin: Cell-size and Body-size. 

 T. H. Morgan: The Development of Isolated Blasto- 



meres of the Egg of Amphioxus. 



G. W. Pibld: Spermatogenesis of Amphioxns. (By 



title only. ) 



Saturday, December 28, 1895. 

 Bashford Dean: Gastrulation of Teleosts. 

 W. A. Loot: Further Evidence of Primitive Meia- 



inerism in Birds and Amphibia. (By title only.) 

 G. H. Parker: Pigment Changes in the Eye of 



Palssmonetes. 

 G. PI. Parker: Reaction of 3Ietridium to Food and 



Oilier Substances. 



C. W. Stiles: Some Points in the Anatomy of Anoplo- 



eephaline Cestodes. 

 R. P. Bigelow: Development of Cassiopea from Buds. 



A novel feature of the scientific sessions 

 was the grouping of allied papers, a plan 

 which proved very successful as a stimulus 

 to general discussion. The first session was 

 entirely taken up with papers on protoplasm, 

 the cell and the closely related subject of 

 experimental embryology. Professor Minot, 

 of Harvard, opened with a paper on ' Pan- 

 plasm,' in which the nature of protoplasmic 

 organization was critically discussed. The 

 doctrine now advocated by so many cytol- 

 ogists, that protoplasm is compounded of 

 elementary organic units, such as the ' pan- 

 gens of de Vries, the ' idioblasts ' of Hert- 

 wig, the ' biophores ' of Weismann, etc., was 

 rejected in toto. Protoplasm, he maintained, 

 is a mixture of substances, not of self-pro- 

 pagating units ; and the attempts to distin- 

 guish between living substance and the 

 ' lifeless ' substances associated with it are, 

 in the main, wide of the mark. The entire 

 substance of the cell, the 'panplasm,' is the 



only real unit and must be regarded as a 

 whole. 



Mr. Branley B. Grififin (Columbia) de- 

 scribed the fertilization of the egg and the 

 history of the centrosome in the gephyrean 

 worm, Thalassema. As in echinoderms and 

 many other forms there is no ' Quadrille of 

 Centers.' The centrosome of fertilization is 

 derived from the supermatozoon and the 

 egg-centrosome degenerates after the for- 

 mation of the polar bodies. The sperm- 

 centrosome may be continuously traced, as 

 a distinct black granule, throughout all the 

 stages of fertilization into the cleavage- 

 stages, and at no time disappears. The cen- 

 trosome of the first spindle becomes double 

 at a very early period and passes to the 

 outer periphery of the centrosphere, where 

 a minute amphiaster is formed on each side 

 as early as the mid-anaphase of the first 

 cleavage. This amphiaster is the preco- 

 cious preparation for the second cleavage. 



Prof. E. B. Wilson (Columbia) called at- 

 tention to the fact that the existing confu- 

 sion regarding the centrosome and attrac- 

 tion sphere is probably due in part to the 

 varying effects of reagents on these struc- 

 tures. In Thalassema, as shown by his own 

 observations and those of the preceding 

 speaker, the centrosome appears as a minute 

 black granule after hardening with sub- 

 limate or picro-acetic and staining with 

 iron hsematoxylin. After sublimate-acetic 

 neither centrosomes nor deutoplasm spheres 

 stain, though the general fixation is not infe- 

 rior to that yielded by the other methods. 

 This suggests the possibility that in Toxo- 

 pneustes, likewise, the sublimate-acetic mix- 

 ture may cause the centrosomes to disappear 

 from view. It was however recalled that 

 in certain stages of this same form they are 

 not shown after other reagents, such as sub- 

 limate and Hermann's fluid ; that they are 

 perfectly shown in the maturation spindles 

 of the starfish after sublimate-acetic, but 

 afterwards disappear ; and that Hill's ob- 



