340 INEZ WHIPPLE WILDER. 



PLATE V. 



FIG. 26 Vertical section through the skin of the lateral region of the body of an 

 aquatic larva collected in May and hence in preparation for metamorphosis as is 

 shown by the presence of mitotic figures, and by the invasion of leukocytes. 



FIG. 27. Section parallel with the external surface, through the outer layer of 

 epidermal cells of the skin of an aquatic larva collected in May. 



FIG. 28. Similar section through the inner layer of epidermal cells, aquatic 

 larva collected in May. 



FIG. 29. Vertical section through the skin of the ventral surface of the leg of 

 an aquatic larva collected in May and showing the rapid progress of metamorphic 

 changes, among them the increase in the number of cells by mitotic division, the 

 development of adult acinous glands, the invasion of leukocytes, the atrophy of 

 the Leydig cells, and the formation of the loose corium. 



FIG. 30. Vertical section through the skin of a larva collected in June in which 

 the metamorphic changes in the skin are nearly completed. Note, in addition to 

 the features indicated in Fig. 29, the presence of a capillary network in the loose 

 corium surrounding the acinous gland. 



