132 



THE UNIVERSITY SCIENCE BULLETIN. 



Relation Between the Length of Pigs and the Percentage 

 Thymus by Weight, Using Litter Averages Throughout. 

 Table No. 2 and curve No. 1 are to be considered in this connec- 

 tion. Curve No. 1 shows that as litters made up of larger and 

 larger foeti, as regards length, are examined, the percentage thj^mus 

 by weight increases steadily. There is a marked drop near the 

 center of the curve which cannot be explained, but it does not ob- 

 scure the general tendency of an increase in percentage thymus by 

 weight. It will be noted that the value for the litter of pigs of aver- 

 age length, 27.1 centimeters, has dropped quite appreciably. 

 Whether or not this means that at 24 cm. or 25 cm. the gland 

 reaches its greatest stage of development we do not know; not 

 enough pigs longer than 25 cm. were examined. It would be an 

 interesting problem to work out to see at just what stage the thymus 

 development ceases, and when it commences to atrophy. 



TABLE No. 2. 



