408 PROCESSES INFERRED FROM INDIRECT OBSERVATION 



the thread, for, in the first place, the streaming phenomena, etc., are 

 obviously attributable to soap-formation, and, in the second place, the 

 phenomena observed when a thread, un wetted save with water, is laid 

 across the drop are quite different from those described above. The 

 drop of oil adheres to the thread and forms an elongated ellipsoid, its 

 long axis coinciding with the thread; in fact the drop of oil assumes 

 somewhat the form which' the cell would assume were the phenomenon 

 subsequent to nuclear division, as Biitschli imagines, an increase in 

 surface-tension at the circumference of the equatorial layer. 



Similar phenomena may be obtained with submerged droplets, 

 formed by adding chloroform to the oil to increase its specific gravity, 

 or by droplets immersed in a column of salt solution of varying con- 

 centration the lower layers being saturated, so that the drop floats 

 midway without sinking or rising, only in this case stronger alkali 

 must be used because the greater part of it is washed off the thread in 

 passing it down to the drop through the upper layers of water or salt 

 solution. 



12 3 4 



Fie. 30. Drawings of a case of cell-division in artificial parthenogenesis (sea-urchin 

 egg) illustrating the underlying phenomenon of streaming. "The division began on 

 one side (1) and the protoplasm then flowed in the direction of the arrows (2) in oppo- 

 site directions toward the two nuclei. The connecting-piece becomes empty of proto- 

 plasm and only the pigmented solid surface film is left (3) and finally this also disappears 

 (4)." (After Loeb.) 



The action of alkalies is not confined to those mentioned above but, 

 apparently, the division and accompanying phenomena can be brought 

 about by means of threads dipped in all bases which form soaps with 

 fatty acids. Thus tenth-normal potassium hydroxide or sodium hydrox- 

 ide and a saturated solution of calcium hydroxide, all bring about the 

 division, although the division when calcium hydroxide is used is less 

 rapid than when tenth-normal sodium or potassium hydroxide are 

 employed, because the concentration of a saturated solution of calcium 

 hydroxide is only about twentieth normal. The division and accom- 

 panying phenomena are also elicited in a marked degree by threads 

 dipped in Choline. 



Not only the bases, but the soaps themselves bring about the 

 division; thus if a thread smeared with Choline Oleate be laid across the 

 diameter of a drop of olive oil, the division of the drop will occur, 

 although more slowly than when choline itself is used. This shows that 

 the action of these bases is due to the soap which is formed when they 

 come into contact with the oil and not to hydroxyl ions. 



Now we have seen that the phosphoric acid component of the 

 nucleic acid molecule is probably derived, during nuclear synthesis, 

 from Lecithin or similar Phospholipins. The decomposition of lecithin 

 for this purpose must lead to the setting free either of Choline itself 



