394 Groom . — On the leaves of Lathraea Squamaria 
like glands are only found just outside the ends of the fine 
nerves. 
The excretion of water does not take place through 
stomata, for they are absent from the subterranean scales 
in Lathraea : nor through special water-stomata, which 
are absent in all these plants (excepting that the teeth- 
stomata of the flat scales of Lathraea may be water-pores). 
There is every reason to believe that the capitate glands are 
not appreciably responsible for the excretion of water, for 
they are most numerous where excretion is very slow (Rhi- 
nanthus ), and show no intimate and necessary connexion with 
the ends of the vascular bundles. We are therefore entitled 
to assume that the subterranean scale-leaves of Lathraea are 
the water -excreting organs of the subterranean plants , and that 
this excretion of water is vigorous, inasmuch as the dome- 
shaped glands are numerous. This view is confirmed by 
a fact recorded by Mr. Gilburt (2) in his valuable little paper. 
Mr. Gilburt imagined that the dome-shaped glands excreted 
an acid sap which should serve to dissolve organic substances 
in the soil in order that the solution might be reabsorbed as 
food. This excretion of acid sap, he says, is abundant, for 
4 in the bank from which I have taken my material, and which 
is composed of a light, friable soil, the soil immediately 
surrounding the Lathrea (sic) was saturated with moisture, 
while all beside could be crumbled apart with the fingers.’ 
A number of observers record that liquid as well as air is 
to be found in the pockets. 
This view of the water-excreting function of the subterra- 
nean leaves of Lathraea is confirmed by reference to other 
allied types with subterranean scales. On these latter, as 
well as on the aerial leaves of the same plants, dome-shaped 
glands are found. I take the following anatomical facts 
mainly from Hovelacque’s comprehensive work (3). Bartsia 
alpina is a root-parasite, usually living in humus-laden wet 
earth. Its aerial leaves have dome-shaped glands over the 
fine nerves near the margin of the lower face. The subterra- 
nean scales possess numerous dome-shaped glands and capitate 
