BY MARJORIE I. C'OLLIXS. 



331 



head divided by butli liuiizoutal and vertieal walls, e.g., eertaiu species of 

 Parkia, Entada, Acacia, and Albizzia (3, p. 296), or the head may be shield-like 

 and consist of two layei's of cells (certain species of Mimosa). Glands with a 

 short stalk and a few head cells have been observed in Acacia dud onae folia 

 Willd., A. exsudanti Liiid., and A. leprosa Sieb. (3, p. 296). 



In species of Acacia, A. rupicola F. v. M., A. vertiicij'lua Cunn., .1. armuta 

 R.Br., A. iJtjcHuntha Benth., found in the neighbourhood of Adelaide, the writer 

 observed four distinct types of glandular hair lutherto unrecorded for the genus 

 Acacia. 



A. rupicola. — In Acacia rupicola the mature gland consists of a uniseriate 

 stalk of from three to six small cells surmounted by a large balloon-like head cell 

 (Text-fig. 3). The cells which make up the stalk are not cut oft' from the base 

 of the head cell, but are formed by a series of parallel transverse divisiiais within 

 the stalk rudiment. The head cell appears to be more actively secretory than the 



Text-fig. 3. — Mature glands of Acacia rupi- 

 cola showing uniseriate stalk of varying 

 length and inflated head cell, (x 230). 



Text-fig. 4. — Surface view of glands of 

 Acacia verniciflua showing head cells 

 and upper tier of stalk, (x 230) . 



stalk cells. The glands of A. rupicola. differ from the uniseriate type of gland 

 already recorded for species of Acacia l)y Soleieder, in that the head is always 

 unicellular; they jirobably re)iresent a simpler tvpe of gland than any previously 

 recorded for the Mimoseae. 



Acacia verniciflua. — In Acacia verniciflua the mature gland resembles 

 the type recorded for species of Mimosa with i-hield-like head and consisting of 

 two layers of cells (3, p. 296). Here the normal mature gland is made u]i of a 

 large head of from eight to sixteen radiating cells in a single layer, supported by 

 a stalk of one or two rows of cells (Text-tig. 4n. h). Each row of the stalk nor- 

 mally consists of four cells, but in some cases iiTegnlar divisions may occur, 

 converting the stalk region into a mass of cells of variable number. 



Gland Development. 



After the first horizontal division differentiating the gland rudiment from the 

 epidermis, a second horizontal division parallel to the first separates the head and 

 stalk rudiments (Text-flg. ba-d). The third division is vertical in the median plane 

 of the head, and is followed almost immediately by a horizontal division within the 

 stalk, cutting off a second stalk cell (Text-flg. 5e-f). Further vertieal divisions are 

 now formed in the head, many of which are quite radial, others nearly so. Closely 

 following the first of these vertical divisions in the head, two vertieal divisions 



