288 SUMMARY OF CURRENT RESEARCHES RELATING TO 



subtend branches ; the whole plant is glandular and pubescent. In- 

 crease in thickness of the root begins within the stele itself and not in 

 the pericambium ; the cambium develops as a circular band between 

 the secondary leptome and hadrome, so that normal increase in thick- 

 ness is brought about in exactly the same way as in a dicotyledonous 

 stem. The full-grown root has * numerous stereids. The stem has an 

 interfascicular cambium, and an endodermis is present in the epicotyl, 



End. 



St. 



Fig. 2. — Part of same root.'* x 744. 



\P., pericambium ; other letters as given under fig. 1, on 

 preceding page. 



but disappears in the internodes above. Spherical crystals are found in 

 the cortex and pith, and especially characteristic are the glandular hairs 

 covering the surface of the stem. The mechanical tissues of the leaf 

 are very poorly developed, but there is a dense chlorenchyma, and a 

 parenchyma-sheath conbuning crystals. Stomata are distributed over 

 both surfaces of the blade. Thus the structure is that of a xerophilous 

 plant, which evidently originated in a warm dry climate, possibly Greece 

 or round the Caspian Sea. S. G. 



Structure of Resin-secreting Glands in some Australian Plants. 



— Marjorie I. Collins (Froc. Linn. Soc. New South Wales, 1920, 

 45, .329-36, 12 figs.). An account of the development of glandular 

 hairs found in certain species of the Sapindace*. Leguminoseaj, Compo- 

 sitae and Myoporinea3. In Dodonsea viscosa the hairs are similar to 

 those previously described for 21 el ano discus, being large in proportion 

 to the thickness of the young leaf, and showing a tendency towards a 

 radial arrangement of the peripheral head cells. The first sign of 

 growth is a projection from the epidermis of a papillose cell ; the 

 nucleus divides, and the first wall is formed in a vertical direction. 

 Either of the two cells thus formed may then divide, and the division 

 may be either in a vertical or oblique direction. The mature glands 

 are large peltate hairs which overlap and spread to a considerable 

 distance over the epidermis. 



In Acacia riqncola, A. verniciflua, A. armata and A. pycnantha four 

 types of hairs were found, which have not been previously described. 

 In A. 7'upicola (Fig. 1) the gland consists of a uniseriate stalk of three 

 to six small cells formed from a single stalk-cell, surmounted by a large 

 bead-cell of active secretory character. In A. verniciflua (Figs. 2, o) 

 the stalk consists of one to four rows of four or more cells surmounted 



