BY ALEX. G. HAMILTON. 779 



arching of the tissues. There is also sometimes a closed- 

 in cavity on each side of the domatium. This I have 

 seen in Morinda jasminoides also. The domatium is 2 mm. 

 high, and the transverse measurement 2-5 mm. in large specimens. 

 The interior is thickly lined with thin cottony hairs, and there 

 are besides stalked T-shaped hairs (fig. 8). Stomata are found 

 only in the lower epidermis, and do not extend to the cavity. I 

 have often found in the domatia small hemipterous insects, which 

 apparently are in the habit of frequenting the cavities, for when 

 driven out of one they go straight to another. 



The microscopic structure is much like that in Dysoxyhitn. 

 The palisade-cells occupy half the thickness of the leaf. There 

 is no thickening or thinning of the leaf blade at the domatium, 

 but it curves upward slightl}^, showing a slight protuberance on 

 the upper surface. Vessels occur in the domatium walls. It is 

 difficult to make out the domatia in young leaves on account of 

 the thick felty layer of hairs. But even in the bud stage I could 

 make out that the tissue extension is present. I have not seen 

 this so early in any other plant. 



Group in. 



Viburnum Chinexse, Hook. — The depressions are large and 

 occur in the axils of midrib and veins. They are 6-14 in number. 

 The leaf is thick in texture, light green, but not glossy. The 

 depression is formed by a thinning of the leaf substance, and has 

 sloping sides and an irregular surface. There is a slight thicken- 

 ing of the leaf all round the hollow (fig. 13), and on this and the 

 elevations are tufts of light brown and curled hairs. They are 

 thick-walled, and their contents are arranged in globules like a 

 string of beads. On the thinner veins whei-e there are no domatia 

 a few rows of straight hairs grow. The hollows are about 2 mm. 

 in diameter. Stomates occur on the lower surface of the leaf and 

 in the hollows. The minute structure is as follows: — (1) Cuticle; 

 (2) epidermis of the upper surface with thick walls; the cells 

 containing a considerable amount of light green chlorophyll; (.3) 

 palisade-tissue very full of large chromatophores, passing gradually 



