761 DOMATIA IN CERTAIX AUSTRALIAN AND OTHER PLANTS, 



Group V. Thicker bunches of hcairs at the axils in plants which 



have leaves coated with hairs, as in Psi/chotria loniceroides. 



In groups i., ii. and iii. there may or may not be hairs in the 

 domatium or round the edge of the orifice, or the hairs may be 

 entirely absent. A regular gradation may be traced between all 

 these forms, and it is sometimes difficult to say in which category 

 a particular domatium should go. I think that this arrangement 

 is the most natural, for as will be seen it is much the same as the 

 consecutive steps in the development of the domatium of 

 Pennantia."^ 



Grotip. i. 



Pennantia Cunninghamii, Miers. — In this plant, Domatia 

 probably reach their highest development. They occur most 

 commonly at the first axils of the secondary veins, but are some- 

 times to be found in the axils of the principals and secondaries, 

 and very often on the ramifying veins at junctions (fig. 1). They 

 vary from 9 to 50, and I have counted more than 100 on one or 

 two leaves. They are very constant in occurrence. But some 

 time ago I found two plants on opposite sides of a creek, and 

 within a few yards of each other, in one of which every leaf had 

 upwards of 30, while many on the other had none, and the 

 majority only a few. But this was the only plant out of some 

 hundreds which I examined that was in this condition. On 

 recently visiting these plants, I find that all the young leaves on 

 the plant formerly without domatia have them in normal numbers 

 and perfect in development on the mature leaves. It will be seen 



• Since completing this paper I have observed in Maclcaya bella, Harv., 

 (Acanthacese) rows of white hairs with crimson tips on the main and 

 secondary veins at the axils ; and triangular pouches in the leaves of 

 Eupatorium riparivm, Regel. (Conipositfe). This last is interesting, as it is 

 an herbaceous plant, in whicli Landstrtini supposed domatia did not occur. 

 I have also received, through the kindness of Mr. R. T. Baker, herbarium 

 specimens of Weinmanniapaniculosa, F.v.M. {=AcJ:ama Muelleri, Benth.), 

 which possess the most remarkable domatia I have yet seen. I Iiope to 

 describe these liereafter when I am able to examine fresh specimens. They 

 certainly differ from the five types enumerated above. 



