182 JOHN LEWIS BREMER 



man are given, and the kidney could not be considered fully 

 active till much later. Other authors place the beginning of 

 the involution much earlier. Finally Weber refers to a report 

 by Ahlfeld of a case of the birth at full term of a child with en- 

 tire absence of both kidneys, and suggests that not only the 

 mesonephros but even the kidney may be functionless for ex- 

 cretion in intra-uterine life. English also reports several cases 

 of the obliteration or stenosis of the urinary passages in fetuses 

 and in the new-born. Usually death occurred in the sixth to 

 the eighth month, but in other cases, which were very surpris- 

 ing to him, the child was born healthy, and showed uraemic 

 symptoms only after two or three days. 



One stumbling block was found, however, by Weber in his 

 studies, namely, the conditions existing in the pig. The pig dif- 

 fers absolutely from the other animals he examined by retain- 

 ing an apparently fully functional Wolffian body up to the time 

 when the kidney should be well able, from its anatomical develop- 

 m.ent, to take over the work, leaving no gap when neither is avail- 

 able. But this exception where a continuous secretion is pos- 

 sible, but not proved, should not, in Weber's mind, vitiate his 

 conclusions drawn from so many cases where a continuous 

 excretion is impossible. 



Had Weber gone further in his investigations he might have 

 found more of these exceptions. Among mammals the cat, 

 the sheep, the opossum, and in other classes the birds and rep- 

 tiles all retain a functional mesonephros until the kidney is 

 ready, the lizards using the provisional organ, according to 

 Wiedersheim, sometimes for a year or more after hatching. 

 Of the continuous activity of the urinary organs in the lower 

 forms Felix seems to have had no doubts; his statements refer 

 only to mammals and to the supposed error of assuming the 

 sequence of events to be the same in mammals as in birds and 

 reptiles. But if many mammals, and those of quite different 

 orders, are found to show the possibility of a continuous urinary 

 excretion, the status of the urinary organs is more and more 

 established, and it is increasingly hard to believe that this con- 

 tinuous excretion is not universal. 



