452 Brooks : The Fruit Spot of apples 



a fairly complete morphology of the fungus in question. In 

 young stages of fruit spots and in all dilute solutions the hyphae 

 are hyaline, granular, apparently non-septate, and are from i 

 to 2 fi in diameter. In more concentrated solutions they are 

 usually granular and hyaline, have a diameter of 2 to 3 //, and are 

 broken up into cells having a length of 30 to 100/i. Stromatic 

 hyphae and those in the pockets of the host tissue are vari- 

 ous shades of yellow and brown in color and are composed of 



* 



thick-walled, somewhat barrel-shaped cells about 5 ft in diam- 

 eter and 6 to 20 ft in length. Chlamydospores are a com- 

 mon accompaniment of these coarse threads. They are brown, 

 thick-walled and have a diameter of from 4 to 6 ft. In young 

 liquid and agar cultures conidia are produced from knob-like pro- 

 jections on the side of long, branching, septate, apparently vege- 

 tative hyphae. Many conidia are produced from a single one of 

 these projections. The conidia are hyaline, granular, one- to five- 

 celled, from 2 to 2.5 ft in diameter and from 15 to 80// in length. 

 In outline they are straight, curved, or sigmoid. They germinate 

 rapidly, sending out one or more hyphae from each cell. In some 

 media the germinating spores produce other spores directly with- 

 out the development of a mycelium. In old cultures a stroma is 

 produced from which arises a layer of hyaline conidiophore- 

 They are from 20 to 60 ju long and differ from the vegetative 

 hyphae but little save in a reduction in length and branching. The 

 conidia and their manner of production are similar to that descnbe 

 above. Pustule-like cavities having no special peridium develop 

 at stomata and lenticels beneath the epidermis. Later they rup- 

 ture the epidermis, exposing a layer of hyaline, septate, sparing, 

 branched conidiophores. The conidia are produced from kno - 

 like projections on the conidiophore and have the characteristics 

 given above for spores produced in culture media. 



The structure of the pustules and of the spores places t c 

 fungus in the genus Cylindrosporium. Of the species in this genus 



enumerated in Saccardo, it bears closest resemblance to 



Cylindro- 



sporium Ranunculi (Bon.) Sacc. This fungus was isolated r° 

 leaves of Ranunculus acris and Ranunculus bulbosus in Italy- 

 far as can be determined, it differs from the apple fungus in ^ 

 manner of freeing its spores and probably also in the structure 



