356 s. HATTA : 



observe ou either side the cross-section of the collecting; duct 

 {cd.) together with a part of the fourth tubule [ptA) ; the longi- 

 tudinal section of the fifth tubule (pLo) is seen on the right 

 side of fig. IOC), standing in wide communication [nst.ô) with the 

 body cavity. This is the hindmost tubule. In the sections lying 

 behind this, the cross-section of only the segmental duct is 

 repeated. 



Thus the tubules of the second pair undergo, at the present 

 stage, complete degeneration. This process begins, in this case, 

 as above seen, at the nephrostome and proceeds upwards to the 

 collecting duct, — a process which is just the reverse of what 

 is observed in the reduction of the tubules of the sixth pair and 

 probably also of the first pair, in Ijoth which cases the tubules are 

 first cut oft from the collecting duct and the scîparation from the 

 peritoneal cavity follows afterwards. 



Period 6. 



In the Stage vi, embryos have developed so far that all 

 the organs have received their definite forms and proper position 

 with the exception of the middle and the hind portion of the gut, 

 whose development is much delayed on account of the yolk-mass. 

 Having absorbed the yolk-granules, the component cells of most 

 organs are much diminished in size. 



Figs. 107-110 have been drawn from a series of sections 

 through an embryo in this stage. The enteric canal {fg.) is much 

 diminished in diameter, presenting, in section, an elongated heart 

 shape. The peritoneum becomes very thin in all its parts with the 

 exception of the pericardium and the coat of the inuicm arteriosm, 

 in which iio component cells are of cylindiical or cubical bbape. 



