144 Papers from the Marine Biological Laboratory at Tortugas. 



The above results taken as a whole admit of only one interpretation. 

 If NaOH prevents the normal functioning of many dififerent types of cells 

 without appreciably entering those cells, we must conclude that its efTect is 

 on the surface and that the alteration in function is connected with a change 

 in the surface layer. Muscle contraction, nerve conduction, and the move- 

 ment of cilia and modified cilia (swimming-plates of the ctenophores) must 

 all be dependent, primarily, on changes in the surface layer of the muscle, 

 nerve, or ciliated cells. 



CYTOLYSIS OF MARINE EGGS. 



Cytolysis of marine eggs is accompanied by (i) an increase in volume of 

 the egg as a whole; (2) in many cases a solution of the yolk and pigment 

 granules. 



Two quite distinct views have been held as regards the cause of the 

 swelling: (i) Swelling may be due to an increase in permeability of the 

 egg surface-membrane such that the salts of sea-water can readily pass in; 

 they therefore no longer balance the osmotic pressure of substances within 

 the egg and the egg swells; (2) swelling may be due to a breakdown of 

 protein, lipoid, or other substances and the development of a higher osmotic 

 pressure or a swelling pressure within the egg. According to the first view, 

 the action of a cytolytic substance must be chiefly on the surface ; according 

 to the second, action is on the cell contents. The relation of cytolysis to 

 penetration of alkali is therefore of special interest as furnishing evidence in 

 favor of one or the other theories of cytolysis. Details of typical experi- 

 ments are given below. 



TOXOPNEUSTES VARIEGATUS (MATURE EGG). 



N/80 NaOH — Egg remains in solution absolutely unchanged for 6 min- 

 utes; diameter 5.5 units ;2^ then swells suddenly to 7.0 units. Color change 

 is coincident with swelling. 



N/80 NH4OH — Color change instantaneous. Egg remains in solution 

 for 15 minutes unchanged; diameter 5.5 units. In the next 5 minutes the 

 egg begins to appear coarsely granular and at the end of 2 more minutes has 

 swollen to 7.5 units and is filled with a mass of globules. Swelling is 

 relatively rapid. 



Eunice fucata (palolo worm) mature egg. 



N/80 NaOH — Egg remains in solution unchanged for 8 minutes ; diame- 

 ter 19 units. Then swelling begins and continues slowly for 5 minutes; 

 diameter 21.5 units. The color change occurs gradually during the 

 swelling. 



N/80 NH4OH — Color change instantaneous. Egg remains unchanged 

 in appearance and size and only becomes broken up into oil-like globules 

 after an hour. 



^ A unit is 19.2 microns. 



