86 C. H. PECK ON THE " BLACK KNOT." 



form. This stage of the fungns development has evidently been 

 mistaken by some for its complete deveL'pment. In the work of 

 Harris, on Injurious Insects, we find the following statement in re- 

 ference to this fungus; "they come to their growth, discharge 

 their volatile seed, and die in the course of a single summer." 

 And in the Practical Entomologist for March, 1866, we find this 

 statement : *' Towards the middle of August, the new black knot, 

 having perfected its seed, gradually dries up, and becomes intern- 

 ally of a reddish-brown colour. In other words, like so many other 

 annual plants, it dies shortly after it has perfected its seed." 

 Again, in the March number for 1867, Mr. Walsh says : " I 

 showed that black knot is nothing but an assemblage of minute 

 funguses, which perfect their seed, or ' spores,' as botanists term 

 it, the latter end of July ; and that consequently, as this fungus 

 is an annual plant, by cutting off and destroying the black knot 

 early in July, its further propagation may be effectually stopped." 



Now, according to all of our observations the seed of the fungus 

 is not perfected in July and August, nor indeed until some months 

 later.^ Externally, it is true, the fungus appears to have attained 

 its full develo])ment, but if one of these little black globes —j^^rz- 

 thecia they are called by botanists — be taken from the tree at this 

 time and crushed on the slide of the microscope, and its contents 

 examined, little oblong, pale membranous sacs will be seen. They 

 are not all equally developed, and are evidently rudimentary. If 

 we again examine the contents of some of the perithecia, collected 

 at a later period, say in November, we shall find that our rudimen- 

 tary sacs have increased considerably in size. They are now cylin- 

 drical, and contain a greenish, grumous endochrome, from which 

 the spores are destined to be formed. The earliest period in which 

 we have found the spores developed isthe middle of January. In 

 specimens collected January 13th, spores were found in a few of the 

 sacs, but most of them were yet filled with their greenish contents. 

 We have found spores in specimens collected as late as June, there- 

 fore the time in which the fungus perfects its seed may be said to 

 be from January to June. Thus it will be seen that the plant is 

 not an annual, as some have affirmed, but one that requires from 

 fourteen to twenty months from the time of its first manifestation 

 as an incipient excrescence to the time of the maturity of its seed ; 

 and from eight to fourteen months from the time of its first ex- 

 ternal appearance as a plant to the perfection of its seed. 



