EXPLANATION OF THE PLATES. 



PLATE LIY. 



Fig. 1. A portion of the parotid gland of an embryo of the 

 sheep four inches long, showing it in the very 

 earliest condition of its development in which it 

 can be traced ; the follicles, although arranged in 

 clusters, are yet separate and independent of each 

 other. After Muller. Magnified 8 diametres. 



Fig. 2. Shows a further development of the parotid gland 

 in the human subject ; in this figure the follicles 

 are closely aggregated in clusters, each cluster re- 

 presenting a miniature lobule. 



Fig. 3. A portion of mammary gland filled with milk glo- 

 bules. 



Fig. 4. A section of liver showing the form of the lobules 

 and the arrangement of the secreting cells. The 

 light spaces in the centre of the lobules indicate 

 the position of the central hepatic veins. 



Fig. 5. A portion of mammary gland, but slightly magnified. 



Fig. 6. Ditto, more highly magnified, showing clearly both 

 its small granular secreting cells and the milk glo- 

 bules. 



