CHANGES DURING PREGNANCY 527 



greater numl>er the same diet was administered before and after 

 pregnancy and during its whole course. The amount of protein did 

 not far exceed the minimal requirement for the maintenance of 

 nitrogenous equilibrium. 



Similarly, variable results were obtained by Jagerroos 1 in the 

 dog. 2 In his Experiment II., in which the nitrogen content of the 

 food was high and the diet was pure flesh, there was a positive 

 balance each week except the second, 27'9 gm. nitrogen in all being 

 retained during pregnancy. In Experiment III., also on a diet of 

 flesh but containing only 5'97 gm. nitrogen per day, a negative 

 balance occurred only in the fifth and sixth weeks; but when the 

 weight of the foetuses and adnexa, and a serious loss of nitrogen soon 

 after labour were deducted, there was a final loss to the mother 

 of more than 6 gm. of protein. In the last experiment the diet 

 consisted of 60 gm. of flesh and 100 gm. of sugar, which was just 

 sufficient to maintain nitrogenous equilibrium. 3 It was maintained 

 for the first few days of pregnancy, and then a loss of nitrogen 

 occurred each w r eek throughout the whole course of gestation except 

 the third. 



Bar has criticised and rightly so the diet given by Jagerroos 

 as unsuitable. The animals did not take the food well, so that at 

 times there was more nitrogen in the excreta alone than in the 

 food. From his criticism and his own observations it is clear that 

 Hagemann's dictum that gestation entails a sacrifice of protein on 

 the part of the maternal organism holds good only when the animal 

 is on an inadequate or unsuitable diet. Bar and Daunay 4 fed three 

 pregnant bitches on a constant diet of bread, water, fat, beef, and 

 salt, and estimated the nitrogen of the urine and fa-ces at regular 

 intervals. They took precautions to secure the young and the after- 

 births, and were able to determine accurately their nitrogenous 

 content. In the three animals, as in two observed by Jagerroos, the 

 period of gestation was triphasic. There was first a period of 

 retention of nitrogen, then a balance or very slight loss, and finally a 

 retention increasing with the progress of gestation. Further, there 

 was over all a gain of nitrogen in two dogs at the conclusion of labour. 

 Hence they conclude that pregnancy in a healthy animal, with a 

 rational and sufficient diet, does not necessitate a drain on her 

 stock of nitrogen to satisfy the needs of the fcrtus. 



The extensive work of Murlin on the metabolism of pregnancy 

 also comprises observations on the nitrogen metabolism. These 



1 Jagerroos, " Der Eiweiss-, Phosphor-, und .Sal/.umsatz wahrend der Gravid- 



itiit," Ar,-/t. f. '/////<>'/-., vol. Ixvii., 1903. 



a Jagerroos and Ver Eeke failed to secure the shed 



3 Calculated over two days only. 



4 Bar and Daunay, !<><. <it. Bar, f<: fit. 



