R C. PUNNRTT AND TIIK LATK P. (1. lUlLKV 5 



vidual (<^ 224) which wiw of thi» wiiuf weight jim it** inothor. An 

 #*! generation (cf. Tiiblo 111, p. 28) wjw nuinKl fnun two iiu'iuIxth of the 

 ^i family which wi»rt» nrurly of thf munv sizf. It conHJHtt**! of 18 indi- 

 vidualHatui oxhibit<Ml the consi<K'nil)lr nm^o nf variation shrwii in Fi^. 11. 

 Points of int<M\»«t an», (n) that the avcrap' weight is rlom* t«» that of the 

 orii^inal small |»ari>nt (AMJ)) ami considtTahly Irns thiiii that <»r thi* 

 Fi gi»nen\tit)n, {h) that only one animal atUiinr«l th«' mean iwircnUil 

 weight, and (c) that in several c^wos animals wore produce<l which win* 

 much smaller than the ori^^inal small jwiicnt (.V 19). As compared with 

 Fi the /*, generation shews a marked shitting towanis smaller size. The 

 numbers are Uh^ small to draw any deduction of value jxh U) there Iwing 

 an increase of variability in F^ jus comjKired with F^. 



The ex[x»riment.s with ^ N \7 are more extensive and have Ix-en 

 ciirrie<l thmugh several genemti»)ns. The 15 F^ animals reared shew a 

 wide mnge of variation, some of them being nearly as small as their 

 nu»ther while othei-s are c«>nsideral)ly heavier than tln'ir father (ef 

 Table 11, p. 22, and Fig. 8). F«)ur /', animals involving time different 

 matings were subse<juently used t<» give an F, generation. These four 

 animals wore all within 1 lb. of one another. The F.^ generation t^iken 

 together exhibits great variability (cf Fig. 3) extending some way 

 beyond the ninge of the original parents on either side. Though the 

 mean of the /T, generation jis compared with that of the F^ generation is 

 shifted towards the smaller size this is not so marked a phenomenon as in 

 the preceding Ciise. In this connection we shall have more to say later. 



It was our original intention to breed an F^ generation from a pair 

 of the heaviest F2 animals as well as from a pair of the lightest. Con- 

 sideration of space however compelled us to restrict ourselves to the latter 

 part of the programme. An F^ generation of 23 was reared from two of 

 the smaller F^ animals (JO 187 and J* 192). As compared with their 

 parentis the mean of this generation again shews some shifting to the left 

 in Fig. 3. At this point it wtis decided to try the effects of continuous 

 inbreeding from the smallest of the ^^3 generation in order to ascertain 

 whether a fairly true-breeding strain of small size could eventually be 

 extracted. It is hoped to expand this part of the experiment in the near 

 future and to test the effects of close inbreeding with considerably 

 larger numbers. 



B. Flemish-Polish cross. A small Polish buck weighing 3 lbs. was 

 successfully mated with two Flemish does. In one c;use the doe (O 138) 

 was more than three times as heavy ;vs the P«»lish buck. A single pair 

 of Fi animals w;vs reared and proved to be nearly interimdiate in size 



