URETER PRESSURE. 185 



loop pigment could be seen within the cells. Only very rarely was the pigment to be 

 found in interstitial tissue about the vessels, except within the capsule. 



Similar results were obtained in other cases, a synopsis of two of which are given in 

 the addenda. 



The following points especially are significant. That there was an 

 absorption of fluid and of pigment. That this did not take place from 

 the pelvis alone, as in spite of the low diffusibility of the pigment it 

 was to be found high up in some tubules. That there is no evidence of 

 a tear into interstitial tissue and that the distribution of the pigment 

 speaks against its being reabsorbed from the interstitial spaces and 

 secreted by the cells of the tubules. That the pressure hardly surpassed 

 a previously measured ureter-pressure. In exp. XVII. it did not reach this 

 point and we can hardly suppose, in view of the pigment-distribution in 

 the other cases that, in this the absorption was not by the tubules even 

 though not found far up in them. 



The macroscopic appearances of these kidneys seems to have closely 

 resembled those obtained by Lindemann and led to a careful search 

 for masses of pigment within the interstitial tissue along the vessels. In 

 several of his experiments the pigment did pass up the tubules to a 

 greater or less extent. In other experiments the pigment or oil was 

 almost solely to be found in the interstitial tissue. The results so at 

 variance with mine I find hard to explain, largely perhaps because so 

 little information as to the prevailing conditions is given. No measure- 

 ments of blood or ureter-pressures seem to have been taken. The 

 injection pressures appear to have been selected arbitrarily. In several 

 of Lindemann's experiments, whether on the extirpated or intact 

 kidney, certain tubules were more or less completely injected. The 

 occurrence and the irregularity of the distribution of these injected 

 tubules Lindemann explains as being due to such tubules having been 

 empty at the time the injection was undertaken. This explanation will 

 I think hardly hold good in my experiments where all the tubules must 

 have been functioning. I rather hold that the high pressure needed to 

 turn the balance in favour of absorption to such an extent as to more 

 than enable it to cope with the secretion and of sufficient duration to 

 allow of the pigment fluid entering the tubules, leads to the closing of 

 the opening of many tubules into the pelvis or obstructing them else- 

 where to a greater or less extent, and that in consequence only those 

 tubules which are fortunately placed and well filled with urine will be 

 injected. As noted also by Lindemann the best injected tubules occur 

 towards the end of the kidney and do not enter through the central 



