Penetration of Marine Tissues by Alkali. 



141 



The subumbrella surface of Cassiopea is covered by a thin layer of epi- 

 thehum and muscle and nerve tissues. The epithelium is outermost, nerve- 

 network next, then come the muscle-fibers, and finally, embedded in the jelly, 

 are clumps of symbiotic algal cells scattered in lines running parallel with 

 the muscle-fibers. 



Microscopic examination of the Cassiopea strips used in the following 

 experiments reveals a layer of red-stained granules near the surface and on 

 focusing downward lines of red-stained granules are observed following the 

 muscle-fibers and appearing to be within them. Transverse sections of 

 the same strips showed, however, that very little more than the outer third 

 of the epithelio-muscle layer contained cells stained in neutral red. The dye 

 is chiefly taken up by globules and granules in epithelial mucus-cells. 

 These granules are practically all cast off in the mucus formed by exposing 

 Cassiopea to chloroform-saturated sea-water or other injurious solutions. 

 Neither nematocysts nor algal cells stain. No definitely stained nerve-cells 

 can be made out, although red-stained granules are present where nerve- 

 cells should be. Only the region of the muscle-fibers away {i. e., toward 

 epithelium) from the contractile fibrils stain. It should be borne in mind, 

 then, in interpreting the following results, that red-stained granules are 

 not present in the immediate region occupied by the contractile fibrils, but 

 are present in a region first reached by alkali diffusing into the tissues and 

 in a region containing the nerve-network, although it is impossible to say 

 whether granules within the nerve-cells are stained or not. It is probable, 

 however, that both nerve-cells and the outer ends of the muscle-fibers con- 

 tain the red indicator. The results are given in the following table: 



Table 3. — Relation between color-change, cessation of contraction, and cessation of 

 conduction in Cassiopea. (Tortugas, July g-io, igii.) 



Alkaline solution 

 N/2S0 concentra- 

 tion in Mg-free 

 sea-water. 



Ammonia 



Methylamine. . . 

 Dimethylamine . 



Trimethylamine , 



Ethylamine . . . . 



Normal propyl- 

 amine. 

 Isopropylamine . 



Tetraethylammo- 



nium hydroxide 



NaOH 



KOH... 

 Sr(OH)j 



Time of 

 exposure 

 to solu- 

 tion in 

 minutes. 



Color change in 

 minutes. 



IS 



2.S 



No color change 

 No color change 



No color change 

 No color change 



Cessation of 



contraction in 



minutes. 



Feeble, S; 

 ceases, lo. 

 2 t0 2.s. . . 



Slight contrac- 

 tion, 4; ceases 

 4-S. 



Feeble, lo; 

 ceases, i8. . 



Feeble, 3; 

 ceases, 4. . . 



Feeble, 4; 

 ceases, 4.5.. 



Feeble, 4; 

 ceases, s . . . 



Feeble, s; 

 ceases, 8 . . . 



Muscles con 

 tract when 

 impulse pass 

 es. Very fee 

 ble, 10. 



Feeble, 8... 



Feeble, 7 . . . 



Cessation of 



conduction in 



minutes. 



Missing,* 10; 

 ceases, 16. 



Missing, is; 



ceases, 20. . , 

 Missing, 2; 



ceases, 3 . . . , 



Missing, 3; 



ceases, 3.S . . 

 Missing, 2; 



ceases, 4. . . 

 Occasional, 3; 

 ceases, 4 



Ceases, 6 . . . . 

 Ceases, 4.5 . . . 



Recovery of 

 contraction in 

 minutes on re- 

 moval to sea- 

 water. 



Slight contrac- 

 tion in 10. 

 4 



Recovery of 

 conduction 

 in minutes 

 on removal 

 to sea-water 



Missing, 3; 

 regular, s 



♦"Missing" indicates that sometimes the impulse can pass from a to c, sometimes not. 



