IO4 EXPLANATION OF FIGURES IN PLATES. 



PLATE VII PHYUvACTINIA CORYLEA, EXCEPT WHERE OTHERWISE INDICATED. 



FIG. 69. Erysiphe cichoracearum. Dispirem stages; third division; polar asters 

 strongly developed. 



FIG. 70. Beaked nucleus and aster in early stage of spore formation ; two super- 

 numerary nuclei at opposite end of ascus and lying with their central bodies on 

 the plasma-membrane of the ascus. 



FIG. 71. Beaked nucleus and aster, opposite which the plasma-membrane is 

 drawn in forming an oval depression. 



FIG. 72. Beaked nucleus with aster strongly developed; central body broader 

 than end of beak. 



FIG. 73. Erysiphe cichoracearum. Metamorphosis of the polar aster to form 

 the plasma-membrane of the spore; early stage in folding over of the rays; two 

 supernumerary nuclei present; transverse section of part of membrane of third 

 spore shown in lower part of figure. 



FIG. 74. E. cichoracearum; the rays have formed broad, bell-shaped membranes 

 about the nuclei ; beak of nucleus lying to the right is cut off and appears in the 

 next section. 



FIG. 75. E. cichoracearum; plasma-membrane of spore almost complete. 



FIG. 76. Spore completely inclosed; beak of nucleus still attached to plasma- 

 membrane ; astral rays have disappeared entirely. 



FIG. 77. 'Stage in drawing in of nuclear beak; central body conspicuous at the 

 tip of beak. 



FIG. 78. Later stage, same process. 



FIG. 79. Ascus with two spores; nucleus in resting condition; chromatin con- 

 spicuously oriented on central body. 



FIG. 80. E. communis; late stage in spore formation; central body and system 

 of astral rays divided; beak scarcely visible. 



FIG. 81. E. communis; ascus with view of stage in spore formation looking 

 somewhat obliquely down upon the end of the spore; two supernumerary nuclei 

 in opposite end of ascus. 



