352 



Edwin F. Hopkins 



Y 



Fig. 43. lesion on the outer bulb scale 



Photomicrograph of cross section through lesion. The accumulation of starch in the cells, 

 and an incipient sclerotium, are visible 



penetration, certain areas on the tulip leaves were marked with india 

 ink, inoculated by dusting with conidia, and, after various intervals, 

 cut out, killed, fixed, and stained. 



On the bulbs, typical necrotic lesions appear, which show a peculiar 

 accumulation of starch about the diseased area. This is pictured in its 

 general features in figure 43, and in more detail in figures 44 and 45, one 

 of which shows a diseased area and the other a healthy one. These 

 starch grains are heart-shaped and large. They react to iodine in potassium 

 iodide in the usual way, and with Flemming's triple stain are colored a 

 beautiful pink. Why they should accumulate in this manner about the 

 lesion is not known. 



