E. H. Whitehead 



177 



^S 



appreciable change, and seem to remain passive. After the latter length 

 is passed, however, they enter upon a phase of activity, the most marked 

 histological evidences of which 



are their great increase in size and /^^"^'^/.^^^^^ 



extreme vacuolation. As this 

 phase reaches its maximum in the 

 embryo of 28 cm., jnst before term, 

 I may pass at once to the appear- 

 ances presented there. A compar- 

 ison of Fig. 7 with Fig. 6 will serve 

 to show the great change which has 

 taken place as seen under a low 

 power of the microscope. The in- 

 tertubular spaces are now very 

 wide and packed with large Ley- 

 dig's cells, which are divided off 

 into lobule-like groups and col- 

 umns by capillaries. Under the 

 high power (Fig. 8) the cells 

 are polygonal with well defined cell-margins, though occasionally these 

 may be indistinct. The nuclei are eccentric in position, and there is a 









Fir,. 7. Pin 2S cm. The intertul)iilar 

 spaces mueh wider than in flsnre rt and 

 packed with large Leydig's cells. Hsema- 

 toxylin and Congo red. X 70. 



C.B. 



^^^ 

 ^^O 



Fig. 8. Pig 2S cm. A small group of Leydig's cells, g, granules ; C.B., ceiltrosphere 

 B. ; r^ reticulum cells. Mallory's connective-tissue stain. X 800. 



striking difference in the structure of the cytoplasm in different parts 

 of the cell. In the vicinity of the nucleus it is condensed, whereas at the 



