83 



angles and the end allowed to rest against the smoked surface of the cylin- 

 der. A pin driven in the pillar prevents the wire from turning to one side 

 because of the friction of its end with the cylinder. As the root absorbs 

 water the pressure upon the column of mercury increases, causing it to 

 rise in the tube lifting the cork and indicator with it. The indicator then 

 marks a continuous spiral course on the cylinder. The hourly variation 

 can be studied by observing the distances between the lines. The supply 

 of water given to the plant must be kept constant. An eight day clock 

 should be used and the apparatus need scarcely be touched until the plant 

 is exhausted. 



The distkibutiox of tropical kekns in Peninsilar Florida. By LirciEx 

 M. Underivood. 

 To one who makes a visit to Florida for the first time, constant surprises 

 appear on every hand ; sand, palmetto and Spanish moss were expected, 

 but the excess of dry pine lands over hamaks, the multitudinous lakes of 

 every size and shape, the comparative purity of the waters, and the variety 

 of elevation apparent in short distances, formed elements that were not 

 looked for and that serve to modify the botanical features of the country to 

 a considerable extent. The river systems are mostly in a north and south 

 direction, and the rivers are sluggish and often rather deep. Throughout 

 the interior of the state, lakes of all sizes are abundant ; twenty-five to 

 thirty lakes in a single township (six miles square) is not unusual. Most 

 of the small lakes are without outlets, and frequently stand in deep hol- 

 lows. Sometimes you may find two lakes a half mile or so apart with a 

 difierence of elevation from 50 to 100 feet. Except for a slight discolora- 

 tion from roots, the water is remarkably clear and few algae were seen. 

 With the exception of river borders where clay and black mud are found, 

 there is everywhere the loose gray sand that rolls under foot of man or 

 beast, making progress slow and tedious, that supports no turf and only a 

 scattered vegetation, that absorbs moisture rapidly, and th^t contains a fine 

 dust that filters through the clothing and renders one black and grimy 

 after even the shortest tramp. Occasional swamps occur where a forme r 

 pond has given way to a bog, or where a small stream is choked up and 

 thus overflows its usual bounds ; here a variety of deciduous trees stand 

 thick together interwoven with the omnipresent and exceedingly spiny 



