— 39 - 



That moss plants are able to be dried completely for 

 some length of time and still retain their power of re- 

 generation has been demonstrated by Schröder. l By way of 

 confirmation, Bryum capillare was dried thoroughly for three 

 weeks, then moistened and the leaves stripped from the 

 stems and placed in conditions favorable for development. 

 In the same time as usual protonema made their appearance. 

 Barbula muralis was dried for two weeks without the loss 

 of protonema production. 



The foregoing experiments have shown that in nearly 

 all conditions , the only requisite for the development of 

 protonema from rhizoids has been the exposnre to light. 

 Either the main rhizoid axis has given rise to side branches 

 which were distinctly protonema in nature, or the continuation 

 of the main axis has become decidedly protonema like. There 

 may, however. be conditions in which the rhizoids even thongh 

 exposed to light do not prodnce protonema branches. The 

 rhizoids from Mniivm leaves in case the normal development 

 of buds is allowed to be carried ont produce no protonema 

 branches. In the same way the rhizoids from the stem did 

 not give rise to protonema branches, but if the growth of 

 the stem is interrupted the rhizoids undertake the regeneration 

 of the plant and produce new leafy shoots, and protonema 

 branches. This manner of growth is quite common when 

 tufts of various plants are inverted so that the rhizoids are 

 exposed to the light and the shoots killed by being covered 

 with soil. 



The experiments which I have carried out show that 

 the protonema do not produce rhizoids with as great readiness 

 as the rhizoids do protonema. This is in Opposition to the 

 view expressed by Frank, 2 since he says in regard to the 

 protonema: "Eben so leicht kann der Faden wieder in ein 

 Khizoid sich umwandeln." A protonema of Bryum capillare 

 was grown on a piece of flower pot until a considerable size 



1 Untersuch, aus d. Bot. Inst, zu Tübingen 2:15 — 21. 1886. 



2 Lehrbuch der Botanik II : 9. 1893. 



