. The effects of inbreeding and crossbreeding on guinea pigs : III. crosses between highly inbred families. \ flc// \ a* > /k f > C2 / / 36 2 /3 ^ /^ fco 9 0>C- 3239OI ^^.^^^y ^ 20 Fig. 19.—Young raised per mating per year, 1916-1919. Effects of seasonal conditions eliminated (Table2). (See Fig. 8 for explanation of symbols.) of parents on the basis of size of litter is shown to be wholly withouteffect. The best single measure which we have of the reproductive efficiencyof the experiments is the number of young raised per year. This isthe product of the young born per year an
. The effects of inbreeding and crossbreeding on guinea pigs : III. crosses between highly inbred families. \ flc// \ a* > /k f > C2 / / 36 2 /3 ^ /^ fco 9 0>C- 3239OI ^^.^^^y ^ 20 Fig. 19.—Young raised per mating per year, 1916-1919. Effects of seasonal conditions eliminated (Table2). (See Fig. 8 for explanation of symbols.) of parents on the basis of size of litter is shown to be wholly withouteffect. The best single measure which we have of the reproductive efficiencyof the experiments is the number of young raised per year. This isthe product of the young born per year and the percentage raised to33 days (actual, not index). Figure 19 shows the tremendous advance EFFECTS OF IXBEEEDING AND CROSSBREEDING. 31 (more than 80 per cent) obtained in the second generation of cross-breeding over the average of the inbred families. The record of theoriginal random-bred stock is surpassed by nearly 15 per cent by. 2 3 ^ Fig. 20.—The percentage born alive, by size oflitter (Table 15), 1916-1919. (See Fig. 8 for ex-planation of symbols.) JOO eo 1^ 20 / 2 3 ^ ^ Fig. 21.—The percentage raised of the youngborn alive, by size of litter (Table 16), 1916-1919. (See Fig. 8 for explanation of ) ^3:« ^^^5* S-^^. -^ ^ ^^^^^ 1 ^^\s CO Cf 1 cc Experiment CC. In fact, it was merely necessary to cross two inbredfamiUes and obtain a second generation (Cl) to obtain an advance of 70per cent over the inbred ancestry and go beyond the random-bred stock. /so JOO so h % ^ ^ ^^ •n /?— CO—Cfi cc ^ B 60 <C 20 */ 2 3 ^ S Fig. 22.—The birth weight of young raised to 33days, by size of litter (Table 19), 1916-1919.(See Fig, 8 for explanation of symbols.) ^3 to V s. ^ ^s ^ •^ S S /9 CO C/ CC -^ / 2 3 -^ S Fig. 23.—The rate of gain per day by size oflitter (Table 20), 191&-1919. (See Fig. 8 forexplanation of symbols.) Another important result|is seen in comparing the advance of 80per cent i
Size: 1512px × 1653px
Photo credit: © Reading Room 2020 / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookauthorwrightse, bookcentury1900, bookdecade1920, bookyear1922
