352 LEWIS V. HEILBRUNN. 



correct by Bellati and Lusanna 1 and more recently by Bonicke, 2 

 who finds that ten volumes per cent, of CC>2 lower the surface 

 tension of water by about one dyne. 



Passage of Hydrogen and Oxygen. Matthews 3 found that if 

 hydrogen be passed through sea-water containing eggs for ten 

 minutes, then oxygen for ten minutes, and once more hydrogen 

 for ten minutes, the eggs thus treated begin to develop. He does 

 not state whether membrane elevation occurs, but we can readily 

 understand that it may well do so, for both hydrogen and oxygen, 

 no doubt, lower the surface tension. 4 As Matthews says he ran 

 the hydrogen through swiftly, the impurities (e. g., SOs, AsH 3 ) 

 could not have been completely removed, and probably, for 

 this reason, continued exposure to hydrogen gas was found 

 injurious. 



Shaking. Matthews 5 finds that shaking will cause artificial 

 parthogenesis in starfish eggs, but met with no success in his 

 experiments in Arbacia. However, McClendon reports that 

 segmentation occurred after shaking in a vial for five minutes. 

 He does not state if membrane elevation occurred, but from a 

 chance experiment of my own, I believe that it may do so. 

 Vigorous shaking would produce a lowering of surface tension 

 in that it would increase the amount of air absorbed (for effect 

 of gases see above) . 



Heat (to 32 or Over}. As is well known, a rise of temperature 

 produces a lowering of surface tension in all cases. McClendon 

 states that exposure to 32 for four minutes is sufficient to produce 

 segmentation, but he does not state if membrane elevation oc- 

 curred. 



Alkalis. Upon the addition of NaOH, KOH, or Na 2 CO 3 , to 

 sea-water, there is an immediate precipitation of magnesium 

 hydroxide. This fact has never been noted by Loeb, McClendon, 

 or Schucking, all of whom have used alkaline sea-water. It is, 



1 Bellati and Lusanna, Atti. 1st Venet. (6), VII. (1889); ref. in Wied. BeibL, 

 XIV., 18 (1889). 



2 K. Bonicke, Dissert., Miinster (1905). 



3 A. P. Matthews, Amer. Journ. Physiol., IV., 343, 1901. 



4 The latter gas was investigated by Bonicke, who found that it lowered surface 

 tension. 



6 A. P. Matthews, Amer. Journ. Physiol., VI., 142 (1902). 



