780 



SCIENCE 



[N. S. Vol. XXV. No. 646 



combination with experimental work may 

 thus give a decisive test of the general 

 chromosome-theory of heredity. 



Maturation Processes in Paramecium cau- 

 datum: Gaet N. Calkins, Columbia 

 University. 



On the Formation of Regenerative Masses 

 in Sponges allowed to degenerate in con- 

 finement: H. V. Wilson, University of 

 North Carolina. 



Silicious sponges (Stylotella, Microciona) 

 kept under favorable conditions in aquaria 

 undergo degenerative changes, resulting in 

 the formation of small masses of unspe- 

 cialized tissue, which lie scattered through 

 the dead sponge, like gemmules in a 

 Spongilla. Such masses when returned to 

 the normal environment transform into 

 perfect sponges. 



The Influence of a Strong Centrifugal 

 Force on the Egg of Arbacia: T. H. 

 Morgan and E. P. Lyon. 



The Influences of External Factors, Chem- 

 ical and Physical, on the Develo-pment of 

 Fundulus Heteroclitus: Charles R. 

 Stockaed, Columbia University. 

 1. Fundulus eggs develop normally, 

 although at a somewhat faster rate, when 

 kept on moist plates entirely out of water. 

 Such embryos are unable to hatch while 

 on the moist plates, but if at any time after 

 the control has begun hatching some of the 

 eggs are immersed in sea-water they will 

 soon begin hatching, commencing usually 

 in about ten minutes after being in the 

 water and all coming out promptly. On 

 hatching the embryos show a positively 

 heliotropic and a negatively geotropic re- 

 action. 



Embryos were kept thirty-three days, or 

 twenty days after the control had begun 

 hatching, on these moist plates without 

 beginning to hatch. The fish Avithin the 

 egg membrane grows in length and absorbs 



its yolk at about the same rate as hatched 

 ones do. They finally die of starvation 

 after having assimilated all of their yolk, 

 being still confined within the egg mem- 

 brane. 



2. These eggs are not entirely immune to 

 osmotic effects though it has often been 

 stated that they are. In weak cane sugar 

 solutions the yolks were observed to swell; 

 this has not been seen even in eggs develop- 

 ing in distilled water, and may probably 

 be due to some change taking place in the 

 sugar after it has permeated the egg mem- 

 brane. In concentrated sugar solutions 

 the yolk shrinks in a somewhat definite 

 manner. A 1.53 m distilled water solution 

 of cane sugar killed the eggs within 

 twenty- three hours. The osmotic pressure 

 of such a solution is about 34.278 atmos- 

 pheres, about twelve atmospheres more 

 than that of sea-water. Some salt solu- 

 tions exerting even a greater pressure do 

 not kill the eggs. The contradiction is 

 possibly due to the eane sugar becoming 

 inverted in the solutions and its pressure 

 is thus more than the amount calculated. 

 On comparing the effects of sea-water solu- 

 tions of sugar with distilled water solutions 

 it was found that a pressure more than 

 double as high in sea-water produced a 

 much less marked effect. Sea-water solu- 

 tions were alkaline and inversion of the 

 sugar was not so likely to occur. 



3. Several lithium salts produced similar 

 and characteristic abnormalities in de- 

 velopment. 



4. Embryos developed in solutions of 

 KCl show no heart beat or circulation of 

 the blood; the circulatory system is also 

 abnormal. NH^Cl produces a general and 

 indefinite effect on development. MnClj 

 causes a definite effect on the early stages 

 of development. MgClj causes the forma- 

 tion of Cyclopean monsters. NaCl causes 

 the embryos to swim abnormally in a 

 twisting spiral course. 



