A Disease of Currant Canes. 



33 



were present, from the bases and sides of which the perithecia w^re pro- 

 jecting. All gradations could be seen, from the simple tubercles covered 

 with conidia, through those bearing one or several perithecia, to tiiose en- 

 tirely covered by clusters. Conidia were present on all of these strotnata. 



A microscopical examination showed, as was suspected, that the fungus 

 in question was none other than JVecfria cumabarina (Tode) Fr. If a peri- 

 thecium be split longitudinally an appearance represented in Figure 9 is 

 produced. It consists of an outer shell composed of coalesced threads. 

 Springing from the bottom of this are numerous club-shaped sacks or asci 

 which converge toward the apex of the perithecium. Each ascus contains 

 eight elliptical spores which are divided into two cells by a cross-wall near 

 the middle. They measure 12-15X5-7 />«'. 



10. Germinating spores of Nectria. 



Cultures of the mature spores were made in acidified potato agar. The 

 upper part of a cluster of perithecia was cut off with a flamed knife, the 

 contents crushed out in boiled water, and dilutions made in the ordinary 

 way. The plates were kept at the room temperature, 70 to 80 °F. The 

 spores swelled and germinated after twenty-two hours. In nearly every in- 

 stance both cells of the spore germinated, each sending out one or two germ- 

 tubes (Fig. 10). The tube more often originates at the end of the 

 spore than at the side. There is often a more or less prominent constriction 

 of the germ-tube at the point where it leaves the spore. 



At this time no septa were present, the protoplasm of the tube being con- 

 tinuous with that of the spore, and faintly vacuolate. After twenty -eight 

 hours branching had begun and a few septa formed. From this time growth 

 advanced rapidly until the threads had branched into a spreading myce- 



