4'4 DISCOVERY REPORTS 



Table 14. Growth of the 'o corpus albicans' group of females during the first pregnancy 



Length (ft.) 



* This is the intersection of the length frequency distributions of immature and mature females; the standard deviation 

 and standard error are calculated from the frequency distribution of the overlapping group (see Text-fig. 33). 



Further information about the average rate of growth in length in the period following puberty can 

 be obtained by considering the average lengths of these and other groups of females known to be 

 recently mature. The means plus or minus one standard deviation and two standard errors are given 

 for each of five groups of recently mature females in Table 15 and plotted in Text-fig. 39. The groups 

 comprise (a) females at puberty ; females which have ovulated once and are (b) primiparous, (c) nulli- 

 parous, or (d) lactating or resting; females which have ovulated twice and are (e) nulliparous or 

 primiparous, (/) in the second pregnancy. (In the groups (d) and (e) the two categories comprising 

 the group have been amalgamated so as to increase the size of the sample for statistical treatment.) 

 With the exception of the nulliparous females, these all represent individuals which became 

 pregnant at the first ovulation and are presumed on average to have attained puberty in July 

 (that is, as primiparous 'o corpus albicans' females). The average date of the other observations is 

 mid-February. The probable mean growth curve of first pregnancy, 'o corpus albicans' females 

 (from Text-fig. 38) has been drawn in as an unbroken line. It passes close to the mean length of 

 the primiparous ' o corpus albicans ' group (B) and through the mean of the nulliparous ' 1 corpus 

 albicans ' group (C). Females in their first lactation, or first resting period with one corpus albicans (D) 

 will be on average a year older than the primiparous 'o corpus albicans' group, and have been 

 plotted in the second year following puberty. It is possible that a very small proportion of the resting 

 females in this group may be older. 



