Karl Pearson and Adelaide G. Davin 
167 
in man*. We believe that until the nature of the hemisesamoid has been 
standardised (for example, it is defined as a hyaline cartilago after Gruber, or 
otherwise), it is unwise to lay stress on any other statistics than those of ortho- 
sesamoids. 
Out of a total of 79 fahellae found in male subjects by the Collective Investi- 
gation 22 were orthosesamoids, and of 28 fahellae found in female subjects 10 were 
orthosesamoids. Accordingly less than a third of the fahellae were osseous, or 
more exactly the chance of a fahella in man being orthosesamoidal is almost "30. 
Thus we should expect in the 79 male fahellae 24 orthosesamoids and 55 hemi- 
sesamoids (as against 22 and 57 observed), and in the 28 female fahellae 8 ortho- 
sesamoids and 20 hemisesamoids (as against 10 and 18 observed). With a standard 
deviation in the males of about 4*0 and in the females of about 2'4, the differences 
of observed and computed are non-significant, or we cannot assert a sex-differen- 
tiation in ossification. This pro tanto is against an intensive stress theory of 
origin, for if orthosesamoids are produced by stress from hemisesamoids, we might 
reasonably expect greater stresses in the male, and a larger proportion of ortho- 
sesamoids in their total. 
Again in a total of 146 right limbs 61 fahellae were found or 41-8 per 100 
limbs. In 141 left limbs 59 sesamoids were found or again 41-8 per 100 limbs. 
It is therefore difficult to accept the statement of the Report (p. 186, (2)) that fahellae 
are rather more common on right than left limbs. In 157 male limbs 76 fahellae 
were found or 48*2 per 100 limbs; in 84 female limbs 27 fahellae were found or 
32'1 per 100 limbs. This shows a greater preponderance of fahellae of all sorts in 
the male, although both sexes have the same ratio of orthosesamoids to hemi- 
sesamoids. This result contradicts that of Gruber (.see our p. 165, (a)) and appears 
opposed to the conclusion drawn by the framer of the Report (p. 186) himself, 
who writes: "sex has little influence on their [i.e. the fahellae s\ frequency." 
The chief value of the statistics! in this Report is the confirmation they 
* Again on the scale of the Collective Iiwestiijutioii Report, Gruber and Pfitzuer between them 
ought to have found bjetween 26 and 27 mesial orthosesamoidal fabellae. They found none. Hence we 
are compelled to suppose either racial differences exist in this respect, or that one or other set of 
observers is in error. 
t A further point is worth recording, namely the correlation between the appearance of fabellae in 
both heads. Clubbing together both sexes and both sides we have 241 limbs showing the following table : 
Presence of Fabellae in the two Heads of M. gastrocnemius. 
Outer Head. 
Present 
Absent 
Totals 
Present 
13 (10) 
20 (23) 
33 
Absent 
57 (60) 
151(148) 
208 
Totals 
70 
171 
241 
11—2 
