rhysiologicnl Studies on Scbistostega osmundacea. 21 



moss, but that too much dampness of the soil is iiyurious to its 

 developme^it. 



Resistance to desiccation. — I took a piece of almost entirely 

 dried-up soil from the cave at Yutanaka and examining it under 

 a microscope obtained the pictures as shown in Figs. 7, 8 and 

 9. In this condition, the filamentous cell of the protonema is 

 very thin, the chromatophores have lost their colour, and the 

 spherical cells are shrunk, with their chromatophores broken or 

 becoming a shapeless mass. The shoots are all dead through 

 desiccation. 



I kept a culturing dish in a H. SO^ desiccator for 4 weeks, 

 until the reduction of its weight had entirely ceased. Taking it 

 out and placing the dish in a hot-house for three months, supply- 

 ing it with water all that time, I found the protonema giving out 

 the reflected light again and renewing its development. 



This fact has been further ascertained by the recent study of 

 B. M. Beistol (2), who observed that when protonema-laden soil 

 was stored in a sealed bottle so as to prevent the loss of moisture 

 therein contained, the moss became dormant, developing resting 

 filaments. He also observed that when the conditions suitable 

 for the development of the protonema were given, — by putting 

 the soil into nutritive solution, — young colourless filaments were 

 produced from the walls of the resting filamentous cells and small 

 discoid chromatophores appeared with the increase of the length 

 of the filaments. This remarkable rejuvenescence took place even 

 after the moss had been bottled for nearly fifty years. 



I put a quantity of soil laden with protonema of the luminous 

 moss in a Petri dish, and kept it there without any supply of 

 water for nearly a year. At the end of that time when I 

 examined the protonema under a microscope, I observed the 



