No. 4.] FUNGOUS DISEASES. 105 



specks. No one knows the cause. It is not a fungous dis- 

 ease. Spraying has no value in checking it. It is supposed 

 to be due to the thinness of the skin of certain varieties of 

 apples, whereby in a dry season the water is given off from 

 the interior of the fruit. We always find these little brown 

 specks with perfectly sound flesh all around them. 



ISIr. Lyman. Are the black knots of the plum and cherry 

 identical ? 



Dr. Sturgis. Yes, sir. 



Question. Is there such a thing as canker of the cherry? 



Dr. Sturgis. It depends on what you mean by canker. 

 A great many things have been given the name of canker. 

 I have seen it caused by the woolly aphis. There are dis- 

 eases of the apple, pear and quince where canker is caused 

 by fungus. I never happened to see it on cherry or plum. 



Prof. Wm. p. Brooks (of Amherst). It occurs to me 

 that we need a little more light on the question of the intelli- 

 gence of the spores. I wish the speaker would make it 

 clear whether it is not a fact that if one of those spores got 

 into the right position in the soil it will, whether onions are 

 planted there or not, germinate. But of course it is not 

 able to carry itself over into another year because it does 

 not find the proper plant to go through its difierent stages. 



Dr. Sturgis. If the spore germinates without finding 

 the proper plant, undoubtedly it perishes. 



Professor Brooks. It will germinate, w^ill it not, pro- 

 vided it gets into the right position in the soil? 



Dr. Sturgis. I hardly think it probable that it could. 



Professor Brooks. Certainly, if the onion spores are 

 buried too deep to germinate, it will take many years before 

 all of them will be brought into the right position in the 

 soil, which I judge must be near the surface. 



Dr. Sturgis. It is a matter of supposition. I think 

 burying it deep would kill it, if anything would. That 

 would be the natural course with most fungous spores. I do 

 not know that expcriuients have been made on the germina- 

 tion of the spores in the soil. 



Professor Brooks. I did not question the speaker's 

 knowledge of this matter. The spore is to be looked upon 

 as similar to the weed seed. If a weed seed happens to get 



