1 REVUE BRYOLOGIQUE 123 
which exhibits normally any strong torsion of the seta. À normal 
dry capsule placed in water will make 3 or 4 complete turns in 
the « negative » direction (i. e. against the sun or the hands of 
the clock). The abnormal capsule behaves quite differently; in 
all the examples I have tried it first makes a half turn in one direc- 
tion, usually the «positive» (ï. e. with the sun), and then another 
half turn in the reverse direction ; thus bringing it back to about 
its original position, but with the semi-detached strip closely 
applied to its proper place on the seta. (This is not due to an 
: ge es, OPposite torsion of the 
ED À seta in the upper and 
lower parts; the results 
were obtained by immer- 
sion of the upper part 
only). 
Isuggest as an explana- 
tion of these facts that the 
seta in the normal condi- 
tion is composed of what 
might be called positively 
twisting tissue, i. e. tissue 
which on passing from the 
normal moist condition to 
the temporary dry state, 
twistsin the positive direc- 
dry seta will therefore 
regain its position on 
moistening by twisting in 
the negative direction.In 
e the abnormal cases T as- 
sume that one longitu- 
dinal half of the seta is 
pt normal, but that the other 
del 4N-DHON half, or some portion of 
. Explanation of the Figure : 
seta of Acanthocladium laxitextum ; b-e. other tance below the capsule, 
twisting, or perhaps of rigid, untwisting Lissue. When therefore 
_ dry to cause a torsion of the seta, one half would attempt to 
twist in one direction, while the other would resist. It is evident 
that this might well lead to the rupture of the issues of the seta, 
tion ; a normally formed 
a, abnormal it, is for à varying dis- 
examples. All X 3. composed of negatively 
on the maturing of the capsule, a period arrivéd sufficiently 
