112 DESCRIPTION OF THE PLATES. 



nucleus of the primary cell, are cylindrical, and 

 are arranged in a spiral. 



Fig. 7. The cliange into cylinders, and the spiral arrange- 

 ment completed. 



Fig. 8. a One of the secondary cells ; its nucleus a mass of 

 young cells, b A secondary cell elongated into 

 a cylinder, each cell of its composite nucleus 

 elongated into a spiral, c The spiral cells, or 

 spermatozoa, free. 



Fig. 9. A bunch of acini, in various states of developement, 

 maturity, and atrophy. The four following 

 figures are diagrams, arranged so as to illus- 

 trate the intimate nature of the changes which 

 occur in vesicular glands when in a state of 

 functional activity. 



Fig. 10. A portion of gland duct with two acini. One of 

 the acini is a simple primary cell : the other is 

 in a state of developement, its nucleus producing 

 young cells. 



Fig. 11. Both acini are advancing; the second has almost 

 reached maturity. 



Fig. 12. The second acinus is ready to pour out its contents, 

 the first to take its place. 



Fig. 13. The second acinus is in a state of atrophy, the first 

 is ripe. 



Fig. 14. Two follicles from the liver of Carcinus mcenas. 

 The colourless germinal spot is at the blind ex- 

 tremity of the follicle. The secreting cells 

 become distended with bile and oil, as they 

 recede from the germinal spot. 



THE STRUCTURE OF THE LYMPHATIC GLANDS. 



PLATE II. Fig. 15. A portion of the germinal membrane of the human 

 intra-glandular lymphatics, with its germinal 

 spots or nutritive centres diffused over it.. 



