LOCALIZED STAGES IN DEVELOPMENT. 



117 



in many conifers, I have seen no variation in tliis species, and two seem to be a constant 

 character in the cypress family. The next or nepionic leaves differ from the cotyledons 

 in that they are shorter, narrower, thicker, distally acuminate, and more permanent. 

 The first nepionic leaves are a whorl of two opposite leaves, alternating with the cotyle- 

 dons (Figs. 4, 4a). They are of the shape described, and about 7 mm. long. This two- 

 leaved stage, in all the numerous individuals observed, is limited to a single pair of leaves. 

 The next stage is introduced by a whorl of four leaves which are so arranged that they 



Jdniperus vikciniana. 



4. Seedling, showing two long, broad cotyledons, o ; nepionic leaves; 1, whorl of two leaves alternating with cotyle- 

 dons ; 2, whorl of four leaves alternating with cotyledons and first whorl of two leaves, followed by whorls of four leaves 

 throughout this stage. X 1.6. -la. plan of arrangement of cotyledons and first two nepionic whorls. Milton, Mass. 



5. Older seedling, showing two-leaved and four-leaved whorls, followed by a stage with three-leaved whorls as repre- 

 sented in diagrams a, b, c. X 1-5. 



6. Typical leaves of adult in alternating two-leaved whorls. X 1.5. a, plan of leaf arrangement. 



7. Elongate vigorous growth of a terminal branch of adult, showing long, broad leaves arranged in three-leaved 

 whorls. X 1.5. a, plan of same. 



8. Abnormal tirfted ("bird's-nest ") growth of adult, .showing elongate leaves arranged in three-leaved or two-leaved 

 whorls. X 1.5. Compare with Fig. 5. a, b, plans of same. 



Figs. 6-8, West Chop, Martha's Vineyard, Mass. 



alternate with the cotyledons and first whorl of two nepionic leaves (Figs. 4, 4a) . Thus 

 up to and including the second nepionic whorl no leaves of the seedling are vertically 

 superimposed. The second whorl of four leaves alternates with the first whorl and there- 

 fore lies above the cotyledons and pair of first nepionic leaves. Other whorls of four 

 leaves succeed the first two, occupying a vertical space of from 6 to 26 mm., and including 



