Minnesota Plant Life. 65 



which oozes out if the flesh, is broken. One kind with bluish 

 gills and juice, gives off, when broken, a distinctive odor some- 

 thing like that of prussic acid and is very deadly. It is not un- 

 common under white pine trees in the northern part of the state. 



A considerable difference in durability exists among the 

 mushrooms and their near relatives. Some of them are delicate 

 and watery in texture, lasting but a few hours after they are 

 mature. Others are spongy, or of a texture like punk, while 

 those found for example on railway ties become hard and woody 

 even before they are altogether mature. 



The true mushrooms are classified into five principal groups, 

 depending upon the color of the spores, i. Forms with black 

 spores. 2. Forms with dark-brown spores. 3. Forms with 

 brown spores. 4. Forms with red or reddish-yellow spores. 

 5. Forms with white spores. Among the dark-brown spored 

 forms are a number of edible species. Here is included the or- 

 dinary edible mushroom which is cultivated for the market. 



It is an easy matter to determine the exact color of mush- : 

 room spores by cutting off the cap close to the stem and laying 

 it down on a piece of paper with the gills towards the paper. 

 Within a few hours hundreds of thousands of spores will -fall to 

 the paper, tracing there the gill-arrangement and demonstrating 

 the precise color of the spores. If with the point of a pen-knife 

 a few thousands of these spores be lifted and placed under a 

 microscope, they will be found to be somewhat egg-shaped or 

 spherical cells usually with smooth walls and provided each with 

 a bit of living substance in the interior. They are produced in ' 

 clusters of four all over the surface of the gills. The gills them- 

 selves are made up of interlaced threads, which, when they come 

 to the surface turn and grow perpendicular to it. Some of the 

 threads expand their ends, upon which four little ears are pro- 

 duced. The tip of each of these bulges out into a tiny egg- 

 shaped spore. A very narrow neck connects each spore with 

 its stalk and when ripe the spore drops off of itself. 



