215 

 Till': j'YCMDir.M <»i' ('i(i\.\(ii;i)i,rs. 



J. .M. Van Hook. 



'I'lic oc'cnrrciicc of ( 'icimiolioliis ;is ;i iciiiisilc. for tlic iiiosi ii;irt nii tlic 

 liiiwtlor.v mildews, li.-is liccii well kiidwii since tlie iieiius was estalilislied in 

 1N."):{; however, liiere seems to have been more interest in t'oiMiiintJ new spe- 

 lies rather than iiotiiiu the \arioiis foi-nis. many of whieli are <h>uhtk'ss 

 caused liy the specilic pails of the host attacked, theii- shape (hdermininji 

 liie shai)e of liie pycnidiiim of tiie parasite. l'"or examph'. w lien a conidi- 

 opliore of a host is coincrted into a pycnidiiim it is entirely different in 

 shape and size from one formed from a perithecinm of a host. 



.Many s|)ecies of this u;eims are now descrihed. most of these hein.t^ named 

 from the host of the powder.\- mildew rather than from the host of the 

 < 'icinnobolus. l-'rom what is already known of the wide variation of the 

 fniitinj; forms of these i>arasites, together with the similarity of descrip- 

 tion of many of their essential parts, much confusion of sjiecies has doiiht- 

 less heon made. It is hoped that critical study of s(-as(inal variation of the 

 parasite upon a sintile powdery mildew host will he made in the fidure 

 alonj; the lines of (irilliths (The Common I'arasite (d' the Tow.lery Mil- 

 dews. P.ull. Torr. r.ot. (Muh, L'C. 1S!»«>. i. 



Most species have been descrihed as i)arasitizinfi the mycelium oi- conidi- 

 (.I)li(U-es of their hosts: however, in at least three cases they ari' reiHtrted 

 on i)erlthecia. Tliese are hy (irittiths on Erysii)he cichoracearum IK'., hy 

 Sacciirdo and Sydow on Uncinula salicis (DC.) Winter and by Cocconi on 

 IMiyllactinia corylea (Pens.) Karst. It i.s not strange that the last two 

 should have been originally called respectively a Phoma and a Phyllosticta. 

 So far as the writer can learn, the ('icinnobolus herein mentioned has not 

 lireviously been reported on the mycelium, coiddioithoie or iiei-ithecium of 

 Podo.sphaera oxycantlie (DC.) de Bary. 



The present brief paper is to show a form exceedingly coiiunon on the 

 P<iw(lery mildew of cherry, here in .Monroe ("oiudy. Indiana. This seems 

 to form fruit only in the perithecia of the host and usually at about the 

 same stage of its maturity. In figures 1 and "_* of the accomi)anying plate. 

 the comparative forms of the attacked and unattacked perithecia are shown, 

 'i'hese figures represent a fair average of a large nund)er examined and 

 measured. It will be ob.served that parasitized fruit bodies are slightly 

 smaller and have only .slightly less developed appendages. Attention is 

 always attracted by the presence of couidia instead of asci when the i)eri- 

 thecia are crushed, though a more critical examination of the exterior will 

 enable one to judge when pycnidia are present. 



These parasites are an extremely interesting and attractive group from 

 an economic view as well as from a morphological one. There has always 

 appeared to be a possiidlity of their employmeid to hold certain of the most 

 • laiigerous powdery mildews in check. 



It would also be an interesting ])robIem to determine the exact relation of 

 the pycnidium of the ('icinnobolus to the perithecinm of the iiost by means 

 (d' a critical stu<ly of staine<l sections made from material siicii as was u.sed 

 in making the accompanying figures. 



