No. 436.] LOCALIZED STAGES IN PLANTS. 



253 



shorter serrature than the others. Usually the lateral leaflets 

 were like the terminal but in some cases were more compli- 

 cated, Fig. 38, having five teeth in the lateral and three in the 

 terminal leaflets. 



In early spring growth from mature plants, localized stages 

 are seen especially well-marked in weaker lateral shoots from 

 the side of the clump. One such is figured, Fig. 39. The first 

 leaf was like the first leaf of the seedling except that it had a 

 greater number of teeth on each of the leaflets. The second 

 leaf was mainly trifoliolate with a trace of the second pair of 

 leaflets at a, which is noteworthy as it is like the leaflet of the 

 seedling in having three teeth. The third leaf has five leaflets 

 and the fourth seven. The later leaves increase the number of 

 leaflets until there are as many as twenty three or even more in 

 a single leaf. In the developing leaf the proximal part is the 

 last formed and oftener shows characters which, being a failure 

 to develop the full characters, maybe compared to the young 

 and considered as localized senescence, in that individual leaf. 

 Similar localized reversion of the proximal part of leaves were 

 shown in the previous paper mentioned {Amer. Nat , Vol. 36, No. 

 361) in Tansy and here also in Geum. They are shown in 

 (•vmiiocladits disiais by Dr. Jackson {Mem. Bast. Soc. Nat. 

 Hist., Vol. 5, No. 4. " Localized Stages in Development in Plants 

 and Animals"). These proximal reversionary leaflets repeat 

 various stages in the development of the typical leaflet of the 

 plant as shown in leaves lettered a to / in Figs. 39 and 40. 

 Leaflets in this part of the leaf may be found representing 

 various steps from the tridentate character at a which is typical 

 of the first nepionic leaf to one of thirteen teeth at /comparable 

 to a much later stage in seedling growth. These leaves also 

 approach nearer to the earlier leaflets in having less auricled 

 bases, a character which is especially noted in the seedling. 

 The leaflets in the adult show an overlapping in the distal portion 

 and distinct separation in the proximal. 



The stages beneath the flower are definite and easily made 

 out. From a typical leaf having a great number of leaflets, in 

 succeeding leaves the number becomes gradually reduced until 

 at some distance below the flower leaves are found having nine 



