(193) 
for Mimulus and not for Torenia, as for the latter the relation is 
just the reverse. In Torenia the two longer stamens are placed in 
such a way with regard to the stigmas, that a bee first loads its 
back with pollen, in order to rub it off on the stigma on its 
farther penetrating the flower. 
Hence, if the irritable stigmas of Torenia had first been examined 
instead of those of Mimulus, the opinion would never have 
prevailed that they should serve to prevent self- and promote cross- 
fertilisation. 
The view of KERNER von MARILAUN !) that the movement of 
the stigmatic lips should serve to carry the pollen to a spot of the 
stigma where it can further germinate is based on the double sup- 
position that the pollen on the stigma changes its place by the 
movement and that not each part of the stigma is fit for its 
germination. Neither the one nor the other assertion I have found 
confirmed. 
In my opinion, therefore, there has hitherto not been given a 
right explanation of the advantage which a plant may draw from 
the possession of irritable stigmas. 
The closing of the stigma after fertilisation with the plant’s own 
pollen is undeniably accompanied by the advantage that not on 
each consecutive visit of insects it runs the risk of being rubbed 
off the stigma to be replaced by pollen of perhaps quite another 
origin. But this advantage is counter-balaneed by the drawback 
that the inferior pollen from a flower of the same piant, can neither 
be replaced by polien of another individual. If the stigmas did not 
close, then, with frequent visits of insects and after its own stamens 
had been emptied, many a flower of Torenia might be crossed and 
for Mimulus the same might take place still before its own stamens 
had been brushed out. 
To this, however the way is closed, and the said consideration 
leads to the conclusion that the advantage can in no case be of 
great importance. 
Physics. — “On the origin of double lines in the spectrum of the 
chromosphere, due to anomalous dispersion of the light from 
the photosphere’. By Prof. W. H. Jurrus. 
(Will be published in the Proceedings of the next Meeting). 
1) Kerner von MarILAUN, Pflanzenleben LL, p. 260. 
(October 23, 1901). 
