The Mode of Growth and Classification of Galls 29 



Four main divisions of the plant have been made and 

 used as terms to express the particular part of the plant upon 



which the gall may be sought. They are root, stem, leaf, and 

 flower. 



I. The root-galls are those situated upon or within the 

 roots, adventitious, fibrous, tuberous, or the taproot, or the 

 rhizomes. 



II. The stem-galls are those situated upon or within the 

 main stem (erect or climbing), the branches, or the suckers. 



III. The leaf-galls are those situated upon or within or 

 enclosed by the blade, the petiole, the stipules, the bract, or 

 the scales ; or any of these parts enfolding larvs. 



IV. The flower-galls are those situated upon or within or 

 enclosed by the calyx, the corolla, the catkin, or the subsequent 

 fruit or seed. 



The fruit, botanically, is acknowledged as a definite and 

 separate organ of the plant, but its inclusion with the flower 

 is due to a three-fold reason : 



(«) It is a direct outcome of the flower, and appears only 

 when the flower has fulfilled its functions. 



(b) In each case that it is galled the galling agency is 

 present before it arrives at maturity. 



(c) There are so few galled fruits that it is not necessary 

 to make a separate division to represent them. 



It may have been noticed by the reader that no reference 

 has been made to the number of the larvje which inhabit the 

 galls. There is, however, a certain uniformity in this respect 

 with all galls, and although it is not of sufficient importance 

 to form a specific feature in nomenclature, reference is made 

 to it in some descriptions of the galls. 



For this purpose the terms " unilarval " and " multilarval " 

 are employed to indicate whether the gall normally contains 

 one larva or two or more larvs. In the case of the aphides, 

 in which there is no larval condition, the term " multinymphal " 

 is used. These terms arc applicable to the rolled and thickened 

 leaves more than to other kinds. 



The modes of pupation and the spots selected for it by 

 those species which pass through a quiescent stage are noted 

 in the synoptical descriptions, to enable the student to know 

 under which conditions to keep living examples of galls. 



