DEPARTMENT OF MARINE BIOLOGY. 1 29 



from the muscle fibrillas) of the epithelio-muscle layer as viewed in a cross- 

 section of the fresh tissue. When treated with chloroform-saturated sea- 

 water, practically all of the stained granules are sloughed off in an abundant 

 mucus. In this mucus the red granules are quickly changed to yellow in the 

 inorganic alkalies, such as NaOH or KOH. If the living tissue is placed in 

 N/250 NaOH, KOH, Sr(OH)o, or NCCHJ^OH. the red granules remain 

 red for a long time (>J^ hour), and in fact only become yellow when they 

 pass out in the mucus. Mucus formation is induced also by alkali or any 

 treatment (dilute acid or heat) drastic enough to be eventually injurious. 

 Nevertheless, the muscles rapidly (2 to 10 minutes in N / 2^0 solution) lose 

 their poiver of contraction and the nerves their pozver of conduction before 

 the color change occurs. 



In ammonia and the amines, on the other hand, the color change takes 

 place in <2 minutes in N/250 solution and only aftenvards (2 to 15 min- 

 utes) do the muscles stop contracting and the nerves conducting. 



Contraction and then conduction cease much less rapidly in N/250 N H^OH 

 and trimethyl amine than in the rest of the amines, in which conduction 

 generally ceases slightly before the muscles lose their power of contraction 

 on direct stimulation. So long as the alkalies penetrate readily, the stronger 

 (more highly dissociated) they are the more toxic they are. But the inor- 

 ganic alkalies are much less toxic than should be predicated from their de- 

 gree of dissociation. Observation shows that they penetrate all cells very 

 slowly, and may produce marked functional changes (cessation of contrac- 

 tion and conduction) before affecting the neutral red indicator. Therefore 

 their point of attack must be the surface of the cell. The above observations 

 on Cassiopca are strong arguments in favor of the view that the essential 

 conditioning change in contraction and conduction is a surface change. 



It is noteworthy, also, that in the inorganic hydroxides, conduction ceases 

 a considerable time before contraction, an exception to the general rule that 

 most poisonous substances affect the muscles of Cassiopea before the nerves, 

 although the nerve network is outermost (nearest the solution). Presumably 

 the alkali can only diffuse into the tissue through the intercellular spaces, and 

 so collects about the nerve network near the surface in sufficient concentra- 

 tion to affect the nerves before the muscles. 



It is a general rule, which holds for many kinds of tissue, that NaOH 

 (taking this as an example of the strong inorganic alkalies) only penetrates 

 after the cells have been affected. Contraction of the muscle bands of Salpa, 

 in which there is no question but that the red-stained granules are within the 

 fibers, ceases before the red is turned to yellow. Movement of the gills and 

 tentacles of Atnphitrite, of the tentacles of Pennaria, of the ciliated cells of 

 palolo trochophores and Toxopneustes plutei, and of the swimming-plates of 

 the ctenophore Beroe ceases in each case before NaOH enters. In NH^OH, 

 on the other hand, the cilia of palolo trochophores and Toxopneustes plutei 

 remain beating long after the neutral red within the cells (not in the cilia 

 themselves) is decolorized. The ctenophore swimming-plate in NH^OH 

 stops beating after the color change has begun but before it is complete, and 

 the same is true for movement of the gills and tentacles of annelids and the 

 tentacles of Pennaria. 



The relation between penetration and cytolysis of marine eggs is of special 

 interest. Every egg thus far tested (including, besides those already men- 

 tioned, Fissurella, Cumingia, and Chcrtopterus) has proved to be instantly 

 penetrated by NH^OH, so that the color change always occurs before the 

 ^SS begins to swell or, indeed, before it is injured. The same is true of the 

 amines. Cytolysis ensues later, after a certain interval. 



9 — YB 



