PERISPORIACE^!. 283 



191), which constitutes the carpogonium, and which is soon 

 divided by cross-partitions into several cells. From below 

 the spiral there pushes out a branch (the antheridium), which 

 grows upward, and brings its apex in contact with the upper 

 cells of the carpogonium (B, Fig. 191). After this pro- 

 cess, which constitutes fertilization, other branches grow up 

 around the carpogonium, and finally completely enclose it 

 as in the parasitic genera described above (C, D, E, and F, 

 Fig. 191). By the subsequent growth and division of the 

 enveloping branches, the carpogonium becomes imbedded in 

 a thick parenchymatous mass. In the meantime, from the 

 cells of the carpogonium branches bud out and penetrate the 

 surrounding parenchyma (F, Fig. 191), and finally produce 

 eight-spored asci on their extremities (G, Fig. 191) ; after a 

 time the asci are dissolved, and the sporocafp, now of a sul- 

 phur-yellow color, contains only loose ascospores, intermingled 

 with the debris of the broken-up asci and parenchyma.* 



The plants of tins order are abundant and easily studied. The 

 following partial list will enable the student to intelligently begin his 

 investigations : 



PARASITIC PLANTS. 



A. Perithecium containing a single ascus. 



Appendages floccose Genus, Sphcerotheca. 



Appendages dichotoinous " Podosphcera. 



~B. Perithecinm containing many asci. 



Appendages needle-shaped, rigid Genus, Phyllactinia. 



Appendages hooked ' ' Uncinula. 



Appendages dichototuous " MicrospJicera. 



Appendages floccose " Erysvphe. 



Sphcerotheca parmosa occurs on wild gooseberries, on whose stems, 

 leaves, and fruits it forms brown felted masses. In its conidial stage 

 it is frequently so abundant on the leaves of roses as to entirely destroy/ 

 them. 



8. Castagnei sometimes occurs upon the hop in such abundance as to 

 destroy the crop. 



* The student is referred to De Bary's " Morphologie und Physiolo- 

 gie der Pilze," etc., 1865, p. 162. A translation of the part relating to 

 the Erysiphei appeared in " Grevillea," Vol. I., p. 152. 



