118 



LAWSON G. LOWREY 



1. The body as a whole 



Table 1 gives the average body weights observed for the vari- 

 ous litters examined, giving however, no indication of their ages. 

 There are, however, some data available by which the age of one 

 litter and the size at birth can be approximately estimated. From 

 these may be roughly estimated the growth rate for the earlier 

 and later stages. 



35 



25 



§ 1.5 



io.3 

 a. 



15 18 25 39 58 84 107 130 



BoOy Length m Millimeters 



157 



191 



215 



242 262 



Fig. 3 Curves showing relative growth of s])inal cord, lungs and ej^eballs. 

 These curves were secured by arranging the average percentage (for the litter) 

 which the organs form of the net body weight, according to the average body 

 length (in millimeters). In certain cases, several litters are combined, the aver- 

 age of the litter averages being taken (see above). The broken line at the right 

 shows the trend of the post-natal relations, as indicated by the observations 

 on the adults. The information thus gained is only general, as there are no 

 indications concerning the age of the specimens, or the rapidity with which 

 the changes take place. 



The largest ovum found in those pig ovaries examined meas- 

 ured 0.177 mm. in diameter. This includes the zona pellucida 

 which measures about 0.020 mm. in thickness (0.010 mm. counted 

 twice in measuring the diameter). From this, the diameter of 

 the mature ovum (including the zona pellucida) is estimated to 

 be about 0. 18 mm. The corresponding volume would be about 



