DOUGLAS MARSLAND 



123 



It is difficult, of course, to believe that ATP, a large and highly polar 

 molecule, can readily penetrate into the cells in significant amounts, and 

 it may not be necessary to postulate such penetration. Perhaps energy 

 from ATP in the surrounding medium is made available at the cell 

 surface, as indicated by the work of Lindberg (15). 



Experiments With Mersalyl Acid (Salyrgan). The experiments of 

 Weber and Portzehl (32) indicate that salyrgan strongly inhibits the hy- 

 drolytic splitting of the high energy phosphate bonds of ATP and conse- 

 (juently studies have been started on the effects of this compound upon the 



Fig. 13. Mersalyl acid-induced 

 weakening of the plasmagol 

 strength. Measurements made 

 exactly 5 minutes prior to fur- 

 rowing. At this time the gel 

 strength reaches the very high 

 cleavage maximum. 



5i 



i 

 O 



o 



600 



e 600 



UJ 



z 

 o 



o 



Z3 



400 



300 



ARBACIA PUNCTULATA 



20 'C. 



200 



\- O 150 

 Z -* 



Hi 



o 



I 



X 



^- 

 o 

 z 



Ui 

 (C 



t- 



UJ 



o 



100 

 90 

 80 

 70 

 60 



50 



0.0C4 M. 

 MET^SALYL ACIO 



O. 



J. 



2 4 6 8 10 



PRESSURE - 1000 L8S./SQ. IM. 



furrowing strength and gel structure of dividing eggs {Arbacia and Chae- 

 topterus). The results so far likewise indicate that energy from the phos- 

 phate splitting can be utilized in building up the structure of the plasmagel 

 system and finally serves to fortify the furrowing reaction. These results 

 are shown in figures 11, 12 and 13. Here it may be seen that salyrgan 

 added to the sea water (10 min. subseciuent to fertilization) at a con- 

 centration (0.004 molal) which is not adequate to block the first cleavage, 

 does nevertheless produce a distinct weakening of the furrowing reaction 

 at each of the temperatures tested. Thus for both Arbacia and Chae- 

 toptervs, a lower (by 500 lb/in.-) minimum pressure is required to block 

 furrowing at each different temperature (figs. 11 and 12). This w^eakening 

 of the furrowing strength is related apparently to a simultaneous weaken- 



