STUDIES OF INHERITANCE IN PISUM. 



II. The Present State of Knowledge of Heredity and 

 \''ariation in Peas.^ 



By ORLAND E. WHITE. 



{Read October 5, 1917.) 



PART I. 



Introduction.- 



Since the publication of Lock's summary of the genetic work on 

 Pisum in 1908, numerous new studies by Tschermak, Hoshino, Pel- 

 lew and others have very much increased our knowledge of hered- 

 ity and variation in this genus. 



The object of the present review is to summarize this new 

 knowledge and correlate it so far as is practicable with the older 

 knowledge, so that those who are interested may know just how 

 much progress has been made and on what basis of fact the ^len- 

 delian analysis of Pisum rests. 



The Materials. 

 The genus Pisum, according to the Index Kezvensis, consists of 

 seven species, possibly only five of which are markedly distinct. 

 The species with their geographical ranges are : 



P. arvense Linn., Sp. PL, yiy. — Europe, Asia. 



P. elatius Bieb., Fl. Taur. Cauc, II., 151. — Reg. ]\Iediterr. ; Oriens. 

 P. formosum Alef., in Bonplandia, IX. (1861), 237. — Reg. Cauca- 

 sus, Persia, Asia Minor, Syria. 



1 Brooklyn Botanic Garden Contributions, No. 19. 



Tliese studies on peas are being carried on in collaboration with the Office 

 of Forage Crop Investigations and the Office of Horticultural and Pomo- 

 logical Investigations, U. S. Department of Agriculture. 



2 The writer will welcome corrections and especially desires to have his 

 attention called to any genetic work on peas that has been overlooked. 



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