38 



to produce stioots, two, three, and in one case five millimeters 

 in length. 



Experiments were performed with several of the species 

 which produced protonema the most readily to see what 

 effect KN0 3 would have upon the regeneration and manner 

 of growth. Barbula muralis and Phascum cuspidatum leaves 

 were grown in 1% KN0 3 without any apparent retardation 

 or change in the manner of growth. Bryum capillare leaves 

 produced protonema, but there was a marked retardation of 

 growth and the filaments did not reach any considerable size. 

 In 2 °/ KNO3 , Barbula muralis still produced a vigorous 

 growth without any marked retardation. The cells were 

 however generally shorter, and the branching more aggre- 

 gated. Bryum capillare and Phascum cuspidatum produced 

 no growth whatever. In 3 °/ KN0 3 , Barbula muralis pro- 

 duced a slight growth but the filaments did not reach any 

 considerable length. 



A series of experiments was also carried out in order 

 to determine the temperature at wich protonema formation 

 would occur. For these experiments Barbula muralis, Bryum 

 capillare, and Phascum cuspidatum were used ; with the 

 results given in the following table. 



Barbula muralis . . 

 Phascum cuspidatum 

 Bryum capillare . . 



Barbula and Phascum produced protonema with as great 

 vigor as 32° at at 19 — 21° C, the temperature of the ordi- 

 nary experiments; but at 36° C no growth resulted. At 

 29,5° C the Bryum leaves produced no growth but were not 

 killed since when exposed to the ordinary temperature, 

 protonema were produced. At 32° C however, the leaves 

 were killed. At 27° C a slight growth resulted but with a 

 very marked retardation. At 24° the growth was to all 

 appearances quite normal. 



19-21° 



24° 



27° 



29,5« 



32° 



36° 



X 



X 



X 



X 



X 





X 



X 



X 



X 



X 





x 



x 



X 





i 



