vni Journal of Agricultural Research voi.xx 



Page 

 ii. Seedling of Chinese colza, showing cotyledons and young leaves 140 



12. Early rosette stage of Chinese colza seedling: A. — Plants from (1) brown 



seed and (2) yellow seeds. B. — Usual form, showing almost entire 

 leaves 140 



13. Early rosette stage of Chinese colza seedling: A. — Plant showing a variation 



in lobing of the leaves. Two months old. B. — Plant showing a varia- 

 tion in lobing of the leaves. Three months old 140 



14. Eate rosette stage of Chinese colza seedling: A. — Usual form. B. — Plant 



showing a variation in lobing of the leaves 140 



15. A. — Pe-tsai. B. — Cross between Pak-choi and Pe-tsai. C. — Pak-choi.... 140 



16. Early flowering stage of Chinese colza: A. — Usual form, showing somewhat 



enlarged stem base and stem-clasping leaves. B. — Plant without en- 

 larged stem base. C. — Usual form, showing glaucous leaves 140 



17. Early flowering stage of Chinese colza: A. — Usual form, showing luxuriant 



growth and long pedicels. B. — Flower cluster 140 



18. A. — Fruiting stage of Chinese colza. B. — Mature fruit of Chinese colza .. . 140 



19. A. — Herbarium specimen of Brassica chinensis L. B. — Herbarium speci- 



men of Brassica campestris 140 



The Influence op Cold in Stimulating the Growth op Plants 



Plates 



20. A. — Blueberry plants, V actinium corymbosum, made dormant without 



cold. B. — Chilled and unchilled blueberry plants 160 



21. A. — Chilled and unchilled plants of grouseberry, Viburnum americanum. 



B. — Chilled and unchilled plants of tamarack, Larix laricina 160 



22. A. — Chilled and unchilled plants of wild crab, Malus coronaria. B. — 



Blueberry plant with one branch stimulated to growth by cold 160 



23. Blueberry plant with one branch kept dormant by heat. A. — Dormant 



indoor blueberry plant as it appeared on February 15, 1912. B. — Same 

 plant photographed May 21 160 



24. A. — Blueberry cuttings starting to grow at 36 F. B. — Blueberry plant 



growing in the dark at 36 F 160 



25. A. — Dormant wild crab stimulated to growth by pruning. B. — Dormant 



wild crabs stimulated to growth by girdling and by notching the stem . . 160 



26. A. — Dormant blueberry buds stimulated to growth by chalking the stem. 



B. — Dormant blueberry bud stimulated to growth by rubbing the stem . 160 



27. A. — Normal spring growth on a blueberry stem. B. — Abnormal spring 



growth on a blueberry stem, due to lack of chilling 160 



28. Blueberry leaf exuding sugar from glands interpreted as osmotic-pressure 



safety valves 160 



29. A plant of bunchberry, Cornus canadensis, the seeds of which do not germi- 



nate without chilling 160 



30. A. — Trailing arbutus, Epigaea repens, flowering sparingly from lack of chill- 



ing. B. — Trailing arbutus plant flowering normally after chilling. C. — 

 Blueberry plant forced into flower in September by artificial chilling. . 160 



31. A. — Abnormal growth of an unchilled blueberry plant. B. — Awakening of 



long dormant plants by artificial chilling 160 



32. Plants brought out of dormancy at a specified time. A. — Blueberry plants 



from a lot that had been kept in a dormant condition by warmth for 

 nearly a year. B. — Representative plants from each of the two chilled 

 lots described under A, from photograph made January 18, 1918 160 



