208 AGRICULTURAL EXPERIMENT STATION. [Jan. 



the wall, and, when fully developed, fall from their attach- 

 ments and become free in the central cavity. These spores 

 correspond in all respects with the brown spores before 

 mentioned as found in small numbers with the winter 

 spores. The latter are undoubtedly developed in special 

 spore cavities, corresponding in structure to those developed 

 on gelatine, which occur sparingly among those producing 

 winter spores (ascosfiores). But I have not yet been able 

 to recognize them in sections of the knot. From the fact 

 stated it becomes probable that this hitherto undescribed 

 fruit form is the -pycnidial fructification of the black-knot 

 fungus, and it may be seen that it corresponds in general 

 with the known -pycnidia of related fungi. 



The spores, which we may designate pycnospores, taken 

 from pycnidia developed on gelatine, germinate in water as 

 promptly and in the same way as those from the knot 

 (Figs. 4 and 5). When sown on fresh nutrient gelatine, 

 their threads develop much more rapidly and branch more 

 freely than in water, as may be seen by a comparison of 

 Figs. 5, c, and 5, d. On gelatine the spots formed by the 

 masses of dark threads become evident to the unaided eye 

 in eight or nine days, and new pycnidia and pycnospores 

 are produced in from nine to ten days, a slightly longer 

 time than that required for their development from the winter 

 spores. I have not yet succeeded in obtaining perithecia 

 with winter spores from cultures. 



Dr. Farlow describes, in his paper, quoted above, four- 

 kinds of spore-fruits, as follows : (1) those producing win- 

 ter spores (ascospores) in sacs; (2) those producing bodies 

 which he terms stylospores, which form has since been 

 named, by Saccardo,* Hcndersonula morbosa; (3) spore- 

 fruits of the type usually known as spcrmogonia ; (4) oth- 

 ers which he calls -pycnidia, which differ essentially, 

 however, from the pycnidia above described. Of these 

 forms the third has not been met with in course of my 

 studies, but it is yet too early to say it is not likely to be 

 found. I have seen, in a few sections, small spore-fruits 

 among the perithecia, which may be identical with Dr. 



* See Sylloge Fungorum, Vol. Ill, p. 445. 



