16 
Pseudacacia. In both the plants a change from a weaker to a more 
intense light calls forth the EON elevated (or “ MES 5 ' position) of 
the leaflets, whilst one from more intense to a eaker eh od a move- 
Leg 
the leaflets hang emi downwards in darkness. With increasing 
light they gradually move up to a n — When, however, 
light positions are detti There are other types of move- 
ment in — plants into which T need not enter he 
Betw re sensitive so-called T-plants and the ordinary 
the extreme forms that are kun classified respectively as B- and T- 
plants. Mr. Nowack is inclined to think that the intermediate forms 
pass over ^w on into one class or the other. Whether this is so or not, 
I am not in a position at present to o say 
Not infre uently I noticed on certain plants groups of leaves, either on 
a particular shoot or at the base of the main axis, the leaflets o which 
exhibited very sluggish movements, and indeed never assumed a 
position, except in direct sunlight. I am inclined to regard these leaves 
` as indicating an improper eatit of the plants bearing them, since in 
several cases in which the treatment was altered, they behaved ran 
to, and nod indistinguishable from, the other leaves of the pla 
Seeing then that the movements of the leaflets are for the ae part 
controlled by variations in a intensity one can see how the weather 
plant may, under special circumstances, serve as a true weather prophet. 
the weather is continudusly fine or ‘continuously wet the plant will 
in the former case continuously prophesy fin and in the latter, wet 
weather. This is because fine weather is bright weather, and light o 
a strong intensity promotes the “ positive ” emen whilst wet weather 
is dull weather, and a weaker light promotes the “ negative " position. 
So long as the weather day after day is constant, a correct forecast will 
be given, it matters not whether 2 or 10 days ahead. The difficulty i is 
to tell when the fine weather will break up, or the wet weather give 
place to fine. 
I will now — the positions which Mr. Nowack regards as pre- 
monitary of electrical disturbance, snow and hail, mist and Tog. 
* Electricity in "the atmosphere ” is indicated by irregular positions of 
the leaflets, some being positive, others negative or horizontal. The 
semi. need aem however, manifest itself in the form of a thunder- 
The rregular position likewise indicates mist or fog; mist 
if Foy slightly s shown fog when more marked. A thunderstorm is 
indicated by a ng of the leaflets so that the upper surfaces are 
convex, the té v concave. I have noticed a tendency for this phe- 
nomenon to recur on the same iis and I regard it as a pathological 
ce tpm but cannot assign a definite cause for it. 
The irregular * fog-position " accompanies especially varying lights, 
aud is prone to occur on plants whose environment is interfered with 
