138 



C. M. JACKSON 



LUNGS 



The lungs (table 16) in rats held at constant body-weight 

 from the age of three weeks to the ages of six weeks and ten weeks 

 appear to lose in weight. (The data at eight weeks are abnor- 

 mally high, as noted in the table). Thus between the ages of 

 three weeks and ten weeks, the lungs apparently decrease from 

 1.04 per cent to 0.91 per cent of the body-weight; or in absolute 

 weight from 0.250 to 0.218 grams, a loss of about 15 per cent. 

 (A slight correction has been made on account of the difference 

 in body-weight). In the few observations upon rats for longer 

 periods beginning at the later ages of six and ten weeks, there 

 appears to be no material change in the weights of the lungs 

 during the experimental periods. 



The lung infections frequently found in older and adult rats, 

 rarely occur before the age of ten weeks, and thus do not affect 

 the present series. As Hatai has already noted, rats during 

 chronic inanition appear to be unusually free from lung infection. 



During inanition in adult rats, the lungs lose weight in about 

 the same proportion as the whole body, thus nearly maintaining 

 their relative (percentage) weight. The loss is slightly greater, 

 however, during chronic inanition (Jackson '15 c). 



TABLE 16 



The lungs; average absolute weight; aver'age percentage of net body-weight and range 



indicated 



• Lungs in one case abnormally heavy on account of post mortem congestion. 



