436 



THE AMEBIC AN NATURALIST [Vol. LI 



arbitrarily made the initial (Pj) individuals of a new 



The system here presented has been used for two or 

 three seasons' work with the two types of hybridization 

 mentioned above, with Raphanus hybridization beginning 

 with highly heterozygous material, and with pure-line 

 breeding of the tepary bean (Phaseolus). It appears, so 

 far, to be adequate and generally satisfactory for all these 

 types of work. 



SUMMABY 



This paper describes a system of pedigree numbering 

 adapted to various types of genetical work with the higher 

 plants. 



Other similar systems secure greater brevity or clear- 

 ness in certain cases, but are usually of less general ap- 

 plicability; the main differences relate to the designation 

 of series and their initial individuals. 



This system provides for polyembryony and somatic 

 variation, and permits of the addition of various other re- 

 finements in cases where they may be needed. The basic 

 scheme is perhaps as simple and convenient as is con- 

 sistent with use for all purposes without change in essen- 

 tial features. 



In this and similar systems, the numbers are cumu- 

 lative; ShuU's non-cumulative system has both advan- 

 tages and disadvantages in comparison. 



To summarize the most essential features of the pro- 

 posed method: (1) the series for a given plant (genus or 

 species) are numbered consecutively; (2) the initial "in- 

 dividuals, ' ' as defined in the records, are denoted by small 

 letters affixed to the series numbers ; (3) in each following 

 generation the individuals are numbered (if sexually pro- 

 duced) or lettered (if asexually produced), an affixed 

 letter indicating a particular part of an individual; (4) 

 reproduction or propagation is always indicated by a 



