1899] APPLIANCES FOR PHYSIOLOGY 259 
ease with which this and some other fundamental biological 
phenomena may be illustrated in plants that makes botany, 
properly used, an indispensable factor for training in biology. 
Very much can be done in its illustration with no appliances at 
all, though for the satisfactory demonstration of some of its 
most important phases, a clinostat is necessary. The cheapest 
clinostat on the market is Wortmann’s, costing $50, a very 
eficient instrument. Where, however, as in elementary work, it 
is the principle of geotropism or heliotropism that is to be 
illustrated, and not their manifestations in some particular plants 
or their parts, the arrangement shown in fig. 2 is ample. A 
ag paomas eight-day clock is altered by a clockmaker so that 
minute hand revolves once in fifteen minutes (to keep within 
ordinary reaction time).*. The hands and surplus wheels are 
femoved, and over the spindle thus left a brass sleeve is fitted, 
marae at its outer end a thin brass disk, two inches in 
“ameter, with a few holes in its edge, revolving in a plane 
= to the clock face. When the clock is horizontal this 
“isk wil carry a small flowerpot and when vertical it will 
mad also a considerable weight though hardly a pot. For 
ilustrating geotropism, one takes two corks about five inches 
"diameter and an inch thick and pins to each of them 
"te in the five’ different extreme possible pees 
wk a a covered with damp chopped saat eRe 
beveled ed in crystallizing dish of a size to pies a 
Seeds ais of the cork over which it is firmly presse : ae 
inch from th be brought out to the heads of the pins ae ar 
brass disk ng Cork. One of the corks is now fastene is = 
ter and ig ‘a tacks pat through the holes in the edge ‘ =e 
The other €pt revolving in a vertical plane on the ieee : 
Xed in rah by, under the same external conditions, 1S Ea 
instructive ne apm In three days the results are aes 
desired in oa » Indeed, this experiment leaves nothing 
€ beauty of its illustration of this particular subject. 
hair = believe that in 
i ing the 
Spring, my instrument this was accomplished partly by ——— 
pe Patty by removing each alternate tooth from the escapement W 
