1892.] NATURAL SCIENCES OF PHILADELPHTA. 165 



in the accepted characteristic of the species. Then we have the so- 

 called fastigiate varieties, as in the Lombardy Poplar, — or in trees 

 with pendulous branches, as in many trees of gardens known as 

 weeping forms. 



To say that branches are geotropic or heliotropic does not teach 

 us anything, they only repeat the actual fact; nor do any of the 

 terms commonly used in mathematical or physical explanations of 

 the supposed cause. 



Some observations I have made in connection with mushrooms 

 are worthy of recording. They do nothing to elucidate the mystery, 

 but they gain for us the certainty that many partially accepted 

 conclusions are wrong, and it is always an advantage to be able to 

 limit the circle in which we have to search. 



I found a quantity of edible mushrooms growing on the sides of a 

 newly made terrace the face of which had an angle of about 34°. 

 The stipes of the mushrooms pushed out at an exact right angle 

 with the plane of the slope ; but about midway the stipe bent 

 upwards, so that the pileus or crown of the mushroom, instead of 

 being parallel to the slope of the bank had, in a great measure, be- 

 come horizontal. As the growth of the mushroom is mainly or 

 only at night, light could have had no influence in determining this 

 direction of stipe or pileus, — nor, it will surely be conceded, could any- 

 thing connected with gravitation or the attraction of the earth. 



Recently, in a coal mine in Schuylkill County, Pennsylvania, at 

 some 500 feet beneath the surface, I noted that the same species of 

 Poll/poms, Agaricus, and other fungi, that grow from the trunks of 

 dead trees, were here also on the wooden supports of the gangways. 

 The Agaricus pushed the pileus downward or upward just as the 

 point of grow'thwas above or beneath a log. Just when the pileus 

 was about to expand and separate from the stipe, which Avas not 

 until the stipe had reached its full length, the latter would curve so 

 that the pileus would be brought into a perfectly horizontal position, 

 as if the agaric were growing on a piece of level ground. No 

 special law governed the direction of the stipe. They might grow 

 horizontally for several inches from an upright log, vertically from 

 the upper side, or downward from the lower side of a horizontal 

 log. When the time came for the expansion of the cap, the already 

 grown stipe would depart from the straight line, and curve so that 

 the cap would occupy the horizontal position as we see them above 

 ground. If the cap were to fully expand, or to be in any rapid 



