12 MASSACHUSETTS HORTICULTURAL SOCIETY. 



stalk and cap of the mushroom. These white strands constitute 

 the whole vegetative system of the fungus and are familiar to us 

 under the name of '■^ spawn." If a portion of these strands is 

 examined under a microscope, it is plainly resolved into a number 

 of very delicate, transparent threads, or, more strictly, tubes, each 

 of which is divided up at intervals by cross partitions. Each 

 tube is technically called a lujpha ; the hyphse together constitute 

 the mi/ceJhon, and it is this mycelium which composes the 

 vegetative system of every fungus. It is usually inconspicuous 

 because of the minute size of the component hyph;e, and because, 

 from the office wiiich it serves, it is usually buried in the sub- 

 stratum upon which the fungus grows ; nevertheless, either as 

 single hyphcie or aggregations of hypha?, it is always present. 



Coming now to the reproductive portion of fungi, it would be 

 utterly out of the question in the course of a single lecture, even 

 to enumerate the variety of spore-forms and their marvellous 

 adaptations to rapid reproduction. I must therefore content 

 myself with certain broad, and therefore imperfect, generaliza- 

 tions. The two principal groups of fungi with which the 

 economic mycologist has to do, are the Basidiomycetes and the 

 Ascoriiycetes, scientific divisions based upon the method of 

 reproduction. The former are characterized by the fact that at 

 maturity the hypha? or the highly developed mycelium give rise to 

 numbers of club-shaped bodies called basidia, usually arising side 

 by side, closely compacted, and pi'oducing on their tips either two 

 or four spores. This spore-bearing layer may either be exposed 

 to the air by special means adapted to that end, or it may be 

 completely enclosed in a leathery case formed from the differen- 

 tiated and toughened hyphae. In the former category are all our 

 mushrooms and toadstools ; in the latter are our common puff- 

 balls. Some idea of the enormous number of spores produced by 

 the toad-stools and puff-balls may be obtained from the statement 

 that each exposed surface of every one of the gills which occupy 

 the lower side of the mushroom cap is composed of closely packed 

 basidia, each bearing four spores measuring about 0.0003 of an 

 incli in length ; while the dust which issues in clouds from a 

 ruptured puff-ball is composed entirely of similar microscopic 

 spores. Each of these spores is capable of producing a hypha, 

 mycelium, and finally the fruiting body. 



In this group of Basidiomycetes — the mushrooms and puff-balls 

 — a few species exist parasitically upon the roots of grape vines. 



