G. Carl Huber 89 



on its axis to a greater or less extent, so as to bring the upper end of 

 the loop of Henle more to the inner side of tlie tubule, nearer to the 

 collecting tubule to which it is attached — in closer relation to the me- 

 dullary rays. This brings the Malpighian corpuscle from a lateral to a 

 more anterior position and the first part of the convoluted portion from 

 a posterior to a more lateral position. This is shown by a number of 

 models presenting the later stages of development. 



Stoerk has called attention to the fact that the Malpighian corpuscles 

 and uriniferous tubules are generally described as presenting in cross 

 sections a round form. This, he states, is, however, not true (at least 

 for fcetal life), as his models show that they present many irregulari- 

 ties. This is to a certain extent true. The Malpighian corpuscles are 

 rarely of exactly spherical form, but show here and there more or less 

 marked depressions and elevations, or they may present a distinctly 

 oval form. The proximal convoluted portion, especially of older stages, 

 is often of a quite regular cylindrical form, now and then for a distance 

 somewhat flattened, but presents as a rule throughout a quite uniform 

 thickness. The tubule of the distal convoluted portion presents often 

 quite marked irregularities of diameter, segments of relatively large 

 diameter being separated by such as show a much smaller diameter; as 

 the tubule presents now and again a sharp bend at one or the other 

 region showing a relatively small diameter, this portion of the tubule 

 may present a quite irregular form. Stoerk lias also described and fig- 

 ured small cecal appendages attached to the distal convoluted portion; 

 these I have not observed in my reconstructions. 



In giving the position of the different parts of the uriniferous tubule 

 in the kidney substance, it is generally stated that the proximal and dis- 

 tal convoluted portions, with the Malpighian corpuscle, are situated in 

 the cortex between the medullary rays, forming the greater part of the 

 cortex. This is confirmed by reconstructions. Further that the distal 

 end of the proximal convoluted portion — the end segment of Argu- 

 tinsky — enters a medullary ray and with a portion of the descending 

 limb of the loop remains in the ray until the medulla is reached. This 

 is true only for certain tubules, for those the Malpighian corpuscles of 

 which are situated in the cortex above the lowermost two or three tiers 

 of corpuscles, that is, for tubules which present a distinct end segment. 

 The descending limb of the tubules, the corpuscles of which are situ- 

 ated in the lowermost two or three tiers which present indistinct end 

 segments, passes almost directly into the medulla and cannot be said to 

 enter a medullary ray. The loops of Henle for the greater part are 

 found in the medulla, some, as stated, barely reaching the boundary 



