Vol. 2 No. 2 



TORREYA 



February, 1902 



ON THE BEHAVIOR OF MUTILATED SEEDLINGS* 

 By Byron D. Hai.sted 



The particular form of mutilation of seedlings here considered 

 is that of the removal of the plumule. Several kinds of plants 

 have been treated in this way during the past twelve months. 

 The first of these was the garden radish, representing a small, 

 large-rooted and short-lived plant. Soon after the seedling was 

 above ground the plumule was removed upon alternate rows of 

 plants, while the other rows were left to grow normally. The 

 first thing to observe was the much deeper green of the coty- 

 ledons of the de-plumuled plants. This was followed by a re- 

 markable elongation of the petiole and increase in size of the ob- 

 cordate blade, the former attaining a length of three inches and 

 the latter a breadth of an inch and a half. These cotyledons 

 were raised at an angle of about 45 ° and the very dark green 

 blade had a thickness nearly double that of the normal cotyledons. 

 A microscopic examination showed that the greater thickness was 

 due to increased size of the cells instead of to a multiplication of 

 the layers. The chlorophyll was excessive and the amount of 

 starch so great as practically to render them black when blanched 

 with alcohol and iodized. The roots grew to nearly market size 

 and had the tests been made with a turnip-shaped sort instead of 

 a long variety, it is very likely that the roots would have been 

 fit for the table. 



The second species was the common morning glory \_Ipomoea 

 purpurea (L.)]. Here the cotyledons are large in the seedling, 



* Abstract of a paper, with several photographs, prepared for the fifth meeting of 

 the Society for Plant Morphology and Physiology at Columbia University, Jan. U 

 I902. 



[The exact date of publication of each issue of Torreya is given in the succeed- 

 ing number. Vol. 2, No. I, comprising pages I-16, was issued January 24, 1902.} 



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