202 



SECRETION AND EXCRETION 



formed by their disintegration (Fig. 112). The first method 

 of forming the intercellular space is schizogenous, and the 

 second, lysigenous. Sometimes the two methods are combined 

 by the space beginning schizogenously and then being enlarged 



FIG. in. Schizogenous resin duct in the 

 young stem of ivy (Hedera helix), as seen in 

 cross section. A, early, and B, later stage 

 in the formation of the duct, g, the mature 

 duct; c, cambium; wb, phloem; b, bast fibers. 

 (After Sachs.) 



FIG. 112. Lysigenous gland in the 

 leaf of Dictamnus fraxinella. B, 

 young gland, with cells beginning to 

 secrete oil; C, mature gland where 

 the secreting cells have broken down 

 and left their secretion within the 

 cavity thus formed; o, large drop of 

 secreted oil. (After Sachs.) 



lysigenously, and to designate this method the term schizoly- 

 sigenous is compounded. 



Interior glands of protodermal origin solely are found in 

 Amorpha, Myrtus, Eugenia, Asarum, Croton, Crotonopsis, 

 and some species of the Moraceae, Urticaceae, Acanthaceae, 

 Saxifragaceae, Crassulaceae, Geraniaceae, and other families. 

 By far the larger number of interior glands, however, are formed 

 by the ground or fundamental meristem. 



