246 STUDIES IN GENERAL PHYSIOLOGY 



added. In doses of 1.3 g. to 100 c.c. of sea-water it is fatal 

 to Tubularia. 



2. KNO 3 inhibited growth when 0.6 g. was added to 100 

 c.c. of sea-water ; regeneration was prevented by the addition 

 of 1 g. of KNO 3 to 100 c.c. of sea-water. NaNO 3 had a 

 weaker effect; regeneration still followed the addition of 1.3 

 g. to 100 c.c. of sea- water; but when 1.6 g. of this substance 

 was added, regeneration did not occur. An experiment on 

 growth gave the following average results; ten specimens 

 were used in each case ; the experiment lasted eleven days, 

 and the temperature was about 16 C. 



Average Growth 



In normal sea-water - 7.3 mm. 



Addition of 0.6 per cent. NaNO 3 - 1.1 

 Addition of 1.0 per cent. NaNO 3 - 0.3 



The greater effect of the potassium over the sodium is less 

 apparent in this experiment than in the chlorine compounds 

 of this metal. 



3. The poisonous action of NH 4 C1 upon Tubularia is very 

 striking. An opaque precipitate is formed at both ends of a 

 Tubularian stem when only 0.06 g. of NH 4 C1 is added to 100 

 c.c. of sea-water. A quantity 0.03 g. to each 100 c.c. of 

 sea-water suffices not only to inhibit all regeneration and all 

 growth, but renders these life processes forever impossible; 

 for when the animals are returned from such a solution to 

 normal sea-water, they no longer regenerate and grow. 



4. In conclusion I wish to direct the reader's attention 

 to Fig. 62, which shows the regeneration and growth of 

 three Tubularian stems taken from the same colony. 

 They had been put into different salt solutions for the 

 same length of time at the same temperature, ab is in 

 all cases the original piece cut from the animal. Fig. A 

 remained in ordinary sea- water. The piece bd had grown at 

 the oral end 6, the piece ac at the aboral end a; the polyps 

 were very sturdy. The diameter of the new stem is nearly 



