IX. COMPARATIVE ANATOMY OF HYPOCOTYL 

 AND EPICOTYL IN WOODY PLANTS. 



FRANCIS RAMALEY. 



The following is an account of the anatomy of seedlings of 

 certain woody dicotyledonous plants. These plants were studied : 

 Ulmus amcricana LINN., Celtis occidentalis LINN., Toxylon 

 pom if cr um RAF., Broussonctia papyrifera (LiNN.) VENT., Li- 

 riodcndron tiilipifcra LINN., Menispermum canadense LINN., 

 Butneria jlorida (LINN.)KEARNEY, Parkinsonia aculeataLiNTx., 

 Cercis canadensis LINN., Gleditsia triacanthos LINN., Amorpha 

 fruticosa LINN., Robinia pseudacacia LINN., Ptelea trifoliata 

 LINN., Ailanthus glandulosa DESF., Schinns molle LINN., Ber- 

 chemia racemosa SIEB. & Zucc., Rhamnus purshiana DC., 

 Vitis cordifolia NLicuyL^EZaeagmts umbellata THUNB., Eucalyp- 

 tus globulus LABILL., Tecoma radicans (LiNN.) DC., Ca- 

 talpa speciosa WARDER, Cephalanthus occidentalis LINN. The 

 order in which they are described is that of Engler and Prantl. 

 This order will be followed throughout. 



The author is under obligation to Professor Conway MacMil- 

 lan, who suggested the subject of the investigation and under 

 whose direction the work has been completed. 



The seedlings were grown at the University of Minnesota 

 during the years 1896, 1897 and 1898. They were examined at 

 different ages so that the original structure of both hypocotyl 

 and epicotyl could be noted as well as the differences brought 

 about through secondary changes. 



For the sake of convenience and uniformity three stages were 

 studied ; these may be designated as first, second and third 

 stages. A seedling with the cotyledons expanded but with the 

 epicotyl undeveloped is said to be in the first stage. Obviously 

 only the structure of the hypocotyl was studied in this stage. 

 In the second stage the epicotyl has elongated and the first foli- 

 age leaves have appeared. In the third stage a considerable 

 number of foliage leaves have been developed and the anatom- 

 ical structure has, to a considerable extent, taken on its perma- 



