294 
Notes. 
For comparison I give the percentages obtained by analysis of the 
substances from Peltigera and Claviceps , as well as those given for 
mycosine and chitosan. 
Mycosine 
Chitosan 
Peltigera 
I 
Claviceps 
II 
c. 
43-74% 
43-97% 
41-69% 
41-33% 
41 - 33 % 
H. 
N. 
7-3°., 
7-3 1 » 
6- 8o„ 
7- 3 2 » 
5-°° >» 
I-3S,. 
6-79 » 
6*io„ 
Nitrogen was present in the substance from Claviceps , but in such 
small amount that I do not think it could have approached anything 
like 7-32%. I had no time to conduct an analysis. 
F. ESCOMBE, B.Sc. (Lond.) 
DIAHELIOTROPISM OF RADIAL MEMBERS. — The 
purpose of the present note is to call attention to the fact that the 
radial stems of Pellionia Daveauana afford a very good example of 
diaheliotropic irritability in a radial member. The stems of this plant 
normally grow parallel to the surface of the ground, the leaves lying in 
the horizontal plane with their superior surfaces uppermost. If the 
plants are suspended freely, and exposed to bright diffuse daylight falling 
parallel to the length of the stem, when the apex is directed towards 
the source of light the stem curves downwards ; and when the apex is 
directed away from the source of light the stem bends upwards : so 
that in both cases the superior surfaces of the leaves on the apical part 
of the stem are as usual exposed to, and the inferior surfaces turned 
away from, the incident light. 
If the plants are kept in darkness for some time, almost the entire 
length of the stem becomes erect, and the leaves face more or less 
irregularly. If such plants are exposed to very weak illumination 
from above, the stems remain horizontal, and the leaves present their 
superior surfaces upwards. Hence the radial stem of Pelliotiia is 
diaheliotropic and also apogeotropic ; but its diaheliotropic irritability 
is very much stronger than its apogeotropic irritability, for quite weak 
diffuse daylight is a stronger directive agency than gravity is. The 
plant thus affords a very good example of a radial stem possessing 
marked diaheliotropic irritability. 
ALFRED J. EWART. 
Botanisches Institut, Leipzig. 
