84 



Development and Shape of Uriniferoiis Tubules 



ment of the sections of the tubules and their relation to the surround- 

 ing tubules are therefore very different. These figures may serve to 

 show graphically the difficulties met with in attempting to predict what 

 particular portions of any given section through the cortex of the kidney 



Fig. 21. A portion of the cortex of two sections of the kidney, from the 

 series from which tubule B, of Fig. 19, was reconstructed. The portions of 

 the tubule represented in these sections are sketched more deeply than the 

 other parts, x 100. For fuller description, see text. 



belong to one uriniferous tubule; a question to which I shall return 

 later. 



From what has been said concerning the various stages of develop- 

 ment of the uriniferous tubules, it may be seen that from a relatively 

 early period in their development — from a stage in which the various 

 parts of the tubules may be considered as differentiated to the extent 



