20 Art. 5— Y. Toda: 



— 15°C., the cells of the protonema were seen to shrink (Fig. 6), 

 but the filamentons cells did not die even at — 20^C. At about 



— 18°, however, the colls of the leaf began to freeze, and finally 

 the shoot itself died. Keeping the temperature from —12° to 



— 20°C. for 44 hours; from —16° to — 19°C. for 20 hours, from 

 -14° to -20°C. for 24 hours ; and from -19° to -20.5°C. for 72 

 hours by the above arrangement ; then taking the moss out and 

 placing it in a hot-house (16° — 25°C.) : in each case the moss 

 showed again the phenomenon of reflected light after a lapse of 

 20 or 25 days. From the above experiments, we can infer that 

 the filamentous protonema lias a strong power of resisting low tem- 

 peratures, and that it can continue to Hue even at —20.5^C. 



V. Influence of Humidity. 



The humidity of the air has a close relation to the growth of 

 the moss, which thrives best when the air has a humidity of 

 above dO%. When the air is dry, the shoots die and the growth 

 of the protonema ceases. When the soil is too damp, however, 

 the formation of shoots is very slow. I. took two pieces of brick, 

 and covering them with the soil on which the moss had been 

 growing, put each of them in a Petri dish, filling one with just 

 enough water to keep the brick moist and the other with much 

 water. I then placed tlie dishes in a hot- house in which the 

 temperature was kept between 16° and 25° (Feb. 1). In the first 

 dish the protonema began its growth in about 10 days. On April 

 12th, I observed that the shoots had grown over the brick in the 

 first dish, but in the second dish only a few protonemata were 

 visible. As for the shoots, there were so few of them that it 

 was very hard to find them. From the above results, it can be 

 inferred that the more clamp the air is, the better the growth of the 



