506 Fr. J. Mathiesen. 



the cells of the mesophyll contained a normal number of 

 chlorophyll-grains. In the majority of the cases chlorophyll- 

 grains were also present in the epidermis of the lower surface. 



Only P. lapponica^ Sceptrum caroliniim and flammea 

 appear to be totally devoid of non-glandular hairs. The 

 leaves were densely covered with hairs in Castilleia pallida^ 

 Euphrasia arctica, Bartschia alpina^ P. hirsuta^ lanata (in the 

 last-mentioned two species especially along the edges of the 

 petiole on the part near the base of the leaf) and capitata 

 (on the lower leaf-surface and the petiole). The non-glandular 

 hairs are from one to several-celled; in Veronica fruticans 

 and Pedicularis capitata they are rather thick-walled, in the 

 others thin-walled, smooth or with fine cuticular striations; 

 only Veronica fruticans had hairs with coarser cuticular 

 warts. 



Glandular hairs were present in all the species: small 

 glandular hairs with a one-celled stalk and two-celled head 

 in the Veronica spp., Castilleia pallida and in especially great 

 numbers in Euphrasia and Bartschia alpina] the last-men- 

 tioned two species had in addition large, peltate glands with 

 a low sunk stalk-cell and a 2 — 4 celled flat head, hke those 

 in Lathræa (Scherffel, Haberlandt and Goebel; com- 

 pare my Figs. 14 and 19). As previously mentioned by Hove- 

 lacque and Percy Groom, large glandular hairs of peculiar 

 structure occur also in the Pedicularis spp. ; here the low 

 stalk-cell is not sunk, and the head is 2-celled (see for in- 

 stance Fig. 23, A and C). All the species of Pedicularis 

 which have been investigated had such glands. 



The above-mentioned special forms of large glands are 

 found only on the lower surface of the leaf and, as pointed 

 out by the above-mentioned authors and as may be seen 

 from my figure 24 and from most of the transverse sections 

 of leaves figured, they are localised under the vein-branches 



