1056 
tE 
The diffieulties may be removed if e > is considered as a value 
with dimensions 0, and then multiplied by a constant C to bring 
the dimensions into order. 
The procedure is the same in other parts of Physics where ex- 
ponential functions are used. Hence the relative density would now 
Td 
become VER or rather, because in this way we should get too 
wl te 
many constants: Ce ‚ so that fe =1. Now we should have 
E 
to take for the entropy not the mean — log P or — log Con 
9 
but the mean — loy PX certain constant extension). If we now 
take g for this constant extension, so that the form within paren- 
theses represents the relative number of systempoints over an ex- 
tension element g*, we get, after multiplication by the usual con- 
stant 4, Pranck’s above discussed formula. 
If besides we multiply the form, the logarithm of which is taken, 
by NJ, we arrive at Terrope’s formula. 
Botany. — “On the mutual effect of genotypic factors.’ By 
Dr. Tine Tammes. (Communicated by Prof. J. W. Morr). 
(Communicated in the meeting of November 27, 1915). 
The varieties of Linum usitatissimum L., which 1 have used for 
my crossing experiments, show three types with regard to the 
breadth of the petals. In two of these, however, the length of the 
petal is the same. 
The broadest and also the longest petal belongs to the so called 
Egyptian flax. I have previously.’) reported on the variability-curve 
and the median value of both length and breadth. In the present 
investigation, however, the use of the mean value was to be preferred, 
because in some cases the measurements could not be very numerous. 
Since this paper only deals with the breadth, it will suffice to give 
the mean value of this dimension only. It is 13.4 millimetres. 
The breadth of the petal was formerly taken and is still taken 
to be the greatest breadth. The colour of the flower of Egyptian 
flax is blue and has been repeatedly discussed before. 
1) Das Verhalten fluktuierend variierender Merkmale bei der Bastardierung. Rec. 
d. Trav. bot. Néerl. Vol. VII, 1911, p. 249. 
ee 
