No. 637] SHORTEE ARTICLES AND DISCUSSION 177 



degree of divergence from type, produced by the factor in ques- 

 tion in a scale in which 10 is the apparent physiological or visible 

 limit and is the type. Thus A^^ and' a^"* represent factors 

 which cause deviations to the physiological limit in opposite 

 directions (self yellow and self black) from the type A (agouti). 

 A* (light-bellied agouti) represents an estimated deviation be- 

 tween ticked bellied agouti (A) and yellow (A"). The order 

 . of effect is more important than a precise estimate of the degree 

 of effect. Decimals and numbers beyond 10 may be used when- 

 ever necessary, in event of grades not believed physiologically 

 possible. A superscript, once adopted, should not be changed, 

 ^vhich also applies to all other symbols. The value of making 

 provision for a system to indicate the order of a multiple allelo- 

 morph series is clear; the numerical symbols will only be used 

 when such a situation is encountered. 



5. Independent Factors. — Independent series of allelomorphs 

 should be represented by different letters or, if desired, by the 

 same letter with different following numbers. Symbols com- 

 posed of two or more letters should not be used. It is suggested 

 that factors with more or less similar effects be represented by 

 the same letter with different following numlbers, as SI, S2, S3, 

 etc. The same symibol may conveniently he used for factors 

 with more or less similar effects in different animals and plants 

 without implying identity. 



6. Doubtful Factors.— In case the formula of an individual is 

 not fully known, the uncertain factor may, if desired. lie repre- 

 sented by a superscript X (or ?) or the whole symbol may be 

 replaced by a dash. Thus CMor C?) means complete 

 ignorance of the factor in series C. CC'^, CC, or C — represents 

 ignorance as to one of the factors in the zygote. If there is 

 partial knowledge, a double (or triple) superscript may be used 

 to indicate the various possibilities. Thus the progeny of the 

 cross CC X C'c^ may be represented by C c"""*, a form which gives 

 more information than C — . 



represrnts'.vsidu.l li.iv.lity of the kind indi-ated/ Thiis'[S-f] 

 is a .-nnvrnirnt m.\\uu\ of r.'i.ivs.ntal ive moditirrs uf the effect 

 produred by the S ( Spotlin- , M'Hes of allelomorphs. Iti a de- 

 tailed stndv of a parrimlar m'oiij) of modifiers, the parenthesis 

 may well contain the lii-ade of efTecf prodiieed by the modifiers 

 in the ease in (piestion. Thus l -^.l'l and [—2.5] might be 

 used to represent tlie modifiers of typieal hooded rats of grades 



