SECRETING CELLS IN GENERAL 



20I 



Fig. 109. — Formation of 

 an interior, globular, ly- 

 sigenous gland of the leaf 

 of Dictamnus fraxinella. 



A, g, g and c, mother cells 

 of the gland; c, from the 

 protoderm, and g, g, from 

 the fundamental tissue. 



B, older stage where the 



sisting of a more or less globular group of 

 cells; and the interior tubular type in the 

 form of a tube or canal. Glands belonging 

 to the first type, commonly known as 

 glandular hairs, arise by the tangential 

 division of a protoderm cell producing 

 a multicellular hair, the apical cell of 

 which enlarges and becomes the secreting 

 cell (Fig. 108, A), or a group of secreting 

 cells may compose the gland at the apex. 

 Nectaries are usually of protodermal 

 origin and their cells are frequently 

 elongated radially in the form of papillae 

 (Fig. 108, 5). 



The interior globular glands arise by 

 the division of a cell or group of cells, „ ^ ,. 



_ cells have begun to form 



usually of the ground meristem, and the secretion. The last 



1 ,, 111* ii. r stage is shown in Fig. 112. 



where these glands he near the surface (After Sachs.) 



the protoderm may by cell-division con- 

 tribute cells to their formation (Fig. 

 109); or sometimes the protoderm 

 alone gives rise to the gland. Glands 

 of the globular type are found in 

 the clove, rind of orange and lemon, 

 etc. (Fig. no). 



An intercellular cavity into which 

 the secretions of the glandular 

 cells are excreted is formed in one 

 of two ways: The secreting cells 

 may split apart at the center of 

 the group and then draw or grow 

 away from the line of separation, 

 Fir. no.— Ass-section through leaving an intcrccllular cavity (Fig. 



a portion of ^^nge peel showing \ ..1 ,. n 



the cavity of an interior, globular m)' ^^ ^hc SCCrctmg CClls may 



gland at g; crystals of hesperidin at break down altogether, leaving 



h; calcium oxalate crystals at /fe. , . . . 



(After Tschirch and Oesterle.) thcU" SCCrCtlOnS in the Cavity 



