1898 | REGENERATION AS EXHIBITED BY MOSSES 179 
tion of rhizoids and buds. The simple cutting of the leaf in 
itself seems to be, however, the important factor, that is, the 
complete separation of the leaf from the stem affords the stimu- 
lus for growth, which is then applied to the production of 
rhizoids and new leafy shoots. 
When the stems of Mnium are stripped of leaves and kept 
in conditions favorable for growth, they will produce new shoots 
which originate as axillary branches. As is often noticed in 
nature, the stems produce an abundance of rhizoids and these 
in greater abundance from the region of the stem which has 
given rise to a shoot. In no case, however, was a production 
of protonemata direct from the stem to be observed, and the 
rhizoids grew for months without giving rise to any protonemal 
branches. The production of new shoots from the stems 
occurred as well in the dark as in the light; in the dark, how- 
ever, the new shoots produced smaller leaves, and were more 
slender and elongated. The shoots used for experimentation 
were laid horizontal, and the lateral shoots grew erect, both in 
the dark and in the light, thus showing a well marked negative 
geotropism. The production of the new shoots was not called 
forth by the defoliation, but only accelerated thereby, since 
whole plants subjected to the same conditions produced new 
shoots as lateral branches, according to the manner of branching 
in nature. The stems also showed quite a distinct tendency to 
the production of shoots from the region of the morphological 
apex. Defoliated stems were grown in a vertical position in a 
moist chamber, part with the morphological apex uppermost, 
part with it directed downwards. The result was that in the 
majority of cases the new shoot appeared a short distance below 
the apical end. In some cases the stems gave rise to several 
shoots, and some of these were often well removed towards the 
basal end. The new shoots produced from the stem as well as 
those produced from the leaves were distinctly positively helio- 
tropic. By reversing the leaf cultures from time to time after they 
had reached the length of a few millimeters, the stem was made 
to assume a zig-zag form due to the heliotropic curvatures. 
