( 306 ) 
in a sealed tube, disinfecting this completely by immersing it in 
alcohol and carrying on the further manipulations in another laboratory, 
the needles melting at 29° could be isolated. Afterwards, when the 
form (44°) had not been used for some weeks, the infection seemed 
to have practically vanished, and, with the usual precautions, the 
needles melting at 29° were stable in the air. 
The conversion of the two forms into each other is readily accom¬ 
plished; the fused mass yields, on cooling, the form melting at 29° 
which by inoculation or in an infected region passes spontaneously 
into the stable form 44° with generation of heat. 
From this it is quite evident that we are dealing with a case of 
dimorphism and more in particular with a case of monotropism 
where the one form is always labile towards the other. 
This research will be communicated in detail in the “Recueil des 
travaux chimiques”. 
Botany. — “ Contribution to the knowledge of watersecretion in 
plants .” By Dr. W. Burck. 
(Communicated in the meeting of September 25, 1909.) 
In a previous paper “On the biological significance of the secretion 
of nectar in the flower ”*) I pointed out the correspondence between the 
secretion of nectar in the flowering period and of water or muci¬ 
laginous fluid in the closed flower-bud. On continuing the investiga¬ 
tion there arose a doubt in my mind as to the truth of prevailing 
views on water-secretion at the surface nf the plant. 
This induced me to make some observations, the results of which 
will he communicated here, which give a different view of what 
is to be understood by water-secretion. 
I propose to show later that these modified views on water- 
secretion are not without significance for our conception of floral 
and extrafloral nectar-secretion. 
Ihe phenomenon that in many herbaceous plants and shrubs 
drops of water are secreted during the night and the early morning 
hours at the tips and margins of the leaves (guttation) is ascribed 
to the power of the roots for forcing up considerable quantities of 
water under favourable conditions; when the air cools down and 
approaches the dew-point this water is forced out in the form ol 
9 These Proceedings, Nov. 28, 1908. 
