222 



TAXONOMIC STUDIES IN THE GENUS CERASTIUM : I 



These values of A are multipliers; the actual value of a character taken from the tables 

 of critical values is multiplied by the appropriate value of A, i.e. the value for seed size 

 (x) being multiplied by A^ ; the value for pollen size (y) by A2, etc. The quantities thus 

 obtained are added together to give the discriminant function (F) for that specimen. F 

 (the discriminant function) is the best linear function of the characters seed size (x), 

 pollen size (y), sepal/petal ratio (z), bract/scarious tip ratio' (u) and petal length/petal 

 cleft ratio (v) to discriminate between the groups A, B and C. 



If the actual mean values, x, y, z, u, and v, for one of the groups A, B or C are 

 substituted in the equation, 



F = Aj X + A2 + A3 u + A4 f + A5 2: 



then a value of F can be obtained which will be a mean value for that group. But F is a 

 linear function so that the mid-points between the mean values of F for the groups will 

 be the point at which probability in classification changes. In other words, if the value 

 of F obtained for an unclassified specimen is nearer the mean value of F for one group 



Table 2 



Critical values of seed size (length in X breadth in y) 



Class No. 



I X h 



Class No. 



I X b 



Class No. 



/ X b 



01 



1542 



35 



2738 



69 



3935 



02 



1577 



36 



2774 



70 



3970 



03 



1612 



37 



2809 



71 



4006 



04 



1647 



38 



2844 



72 



4041 



05 



1683 



39 



2879 



73 



4076 



06 



1718 



40 



2914 



74 



4111 



07 



1753 



41 



2950 



75 



4146 



08 



1788 



42 



2985 



76 



4182 



09 



1824 



43 



3020 



77 



4217 



10 



1859 



44 



3055 



78 



4252 



11 



1894 



45 



3090 



79 



4287 



12 



1929 



46 



3126 



80 



4322 



13 



1964 



47 



3161 



81 



4358 



14 



1999 



48 



3196 



82 



4393 



15 



2034 



49 



3231 



83 



4428 



16 



2070 



50 



3266 



84 



4463 



17 



2105 



51 



3302 



85 



4498 



18 



2140 



52 



3337 



86 



4534 



19 



2175 



53 



3372 



87 



4569 



20 



2210 



54 



3407 



88 



4604 



21 



2246 



55 



3442 



89 



4639 



22 



2281 



56 



3478 



90 



4674 



23 



2316 



57 



3513 



91 



4710 



24 



2351 



58 



3548 



92 



4745 



25 



2386 



59 



3583 



93 



4780 



26 



2422 



60 



3618 



94 



4815 



27 



2457 



61 



3654 



95 



4850 



28 



2492 



62 



3689 



96 



4886 



29 



2527 



63 



3724 



97 



4921 



30 



2562 



64 



3759 



98 



4956 



31 



2598 



65 



3794 



99 



4991 



32 



2633 



66 



3830 



100 



5026 



33 



2668 



67 



3865 







34 



2703 



68 



3900 







