110 BEPORT OF THE COMMISSIONER OF AGRICULTURE. 



eye, are characteristic of this form of rot. The rotted herries remain 

 firraly attached to their supports for a long time, sometimes even till 

 the following spring-. 



The manifestations of the Black-Rot do not always appear as de- 

 tailed above, for not infrequently the first evidence ^3f the disease is 

 the sudden appearance of one or more circular, slightly depressed 

 spots, of a bluish-black color, in the center of which there soon ap- 

 pear a few of the little pimjDles or pustules above referred to. These 

 spots increase in size, the pimples m number, and ere long the berry 

 exhibits the black and shriveled appearance already described. 



These changes are effected in from one to five days, varying with 

 the atmospheric conditions. 



The fungus of the Black-Rot is figured in detail in Plate III. It 

 consists of a vegetative or mycelial growth, which pervades the tis- 

 sites of the berry, turning them brown and ultimately destroying or 

 absorbing their contents, and of several distinct forms of reproduct- 

 ive bodies or spores. 



During the earlier stages of the disease the mycelium is most 

 abundant near the surface of the berry, and liere, at frequent points, 

 just beneath the cuticle, it makes a condensed growth, resulting in 

 the formation of the perithecia or conceptacles destined to contain 

 the spores. In their development these conceptacles raise and finally 

 burst through the cuticle, imparting to the stirface of the berry the 

 pimply or j^ustulous appearance mentioned above. At the apex of 

 the exposed part of each conceptacle there is a minute opening or 

 osteolum through which the spores escape at maturity. 



The spores are ptished out, probably by the absorption of water, in 

 the form of minute worm-like threads, being held together by a kind 

 of mucilage. (See Fig. 1, Plate III.) 



The conceptacles found upon a newly diseased berry are of two 

 sorts; one contains oval or oblong spores, named stylospores, and the 

 other contains much smaller cylindrical spores, called spermatia. 

 These two sorts may form distinct pustules or they may be united in 

 the same stroma,* as illustrated in Fig. 2, Plate III. 



The stylospores germinate freely in water within a space of three or 

 four hours. They throw otit a slender tube, which soon provides itself 

 with septa, branches, and quickly develops into a mycelium in every 

 way like that seen within the tissues of the berry. How long these 

 stylospores may retain their germinative power is unknown, but it is 

 not likely that they hold it through the winter season. Their office 

 is undoubtedly to effect the immediate proi)agation of the fungus. 



What may be the role of the spermatia in the econom}^ of the fun- 

 gus is a matter of speculation. Their very small size and consequent 

 lightness have suggested to the minds of some that their office is to 

 more certainly effect the wide distribution of the fungus. In speak- 

 ing of these bodies in general, in the order Pyrenomycetes, Cornu 

 says: "They are true spores, since they germinate and give out fila- 

 ments, having all the appearance of mycelial threads. *' He regards 

 them as very small conidia, of a siDecial form, borne upon particular 

 arbuscles in protecting conceptacles. They do not in general ger- 

 minate in pure Avater, and they have a rather slow development. 

 Their physiological role appears to be determined by their very small 

 size and the circumstances Avliich their germination requires. 



If the exposed surfaces of the conceptacles above mentioned a. 



* Stroma, the substance in which the peritliecia of some fungi are immersed. 



