163 



which are typical of them all. It began its growth with the 

 stem and enlarged gradually, the width curve closely following 

 just beneath the length curve. Suddenly the width curve crosses 

 above the length curve. This usually takes place in the last 

 interv^al before the stem ceases its most active period of growth. 

 In four cases it did this sooner. The length curve still con- 

 tinues at about the same rate while the width curve keeps on at 

 its increased rate. In some cases the rate is nearly constant, but 

 in others somewhat variable. 



The pileus often continued growing after the stem had ceased 

 to elongate ; and even when it had begun to dry and decrease in 

 length (J, P). In O it enlarged for as many as forty hours after 

 the stem had stopped its growth. 



The width of the stem was at first about 2-3 mm. It soon 

 increased to 3 or 4 mm. when it began to elongate. It remained 

 of the same width until the plant was mature. Before maturity 

 was reached, the stem in some cases decreased about i mm. in 

 diameter, due to the drying of the cells in the parts which had 

 ceased to grow. 



A few plants were marked to determine in what region of the 

 stem the greatest growth took place. A section of the pileus 

 was cut off in each case so that the whole stem, from the ground 

 to the point where it joined the pileus, might be taken into 

 account. The marks were placed 2 mm. apart. The marked 

 mushrooms were very sensitive to injury and for this reason I 

 was not able to get records more than three times from each 

 plant. The records show that the greatest increase in length took 

 place near the top of the stem (see Figure 4). It was usually not 

 in the topmost interval, but in one or two down from the top, near 

 the margin of the pileus. The plants grew for several intervals 

 down the stem, but no growth took place in the lowest ones. 



These results in regard to the position of growth in the stem 

 are similar to those obtained by J. Schmitz * in 1841, from the 

 Hymenomycetes. He divided the stem into thirds and found the 



* J. Schmitz. " Mycologische Beobachtungen als Beitrage zur Lebens- und Ent- 

 wickelungsgeschichte einiger Schwamme aus der Klasse der Gastromyceten und 

 Hymenomyceten." Linnaea i6 : 141-215. 1842. 



