20 BOTANICAL GAZETTE | (juLy 
these roots and those of corn were papillate in air, passage into 
water checked their growth, caused curves, and made the hair longer 
at first, after which the roots grew smooth. Swellings and curves 
are generally covered with long hair, for which he offers the following 
explanation: 
Lorsque les substances plastiques ne sont pas entitrement utilisées par 
Pextrémité végétative, ainsi que cela arrive quand l’accroissement de cette dernigre 
est entravé par une cause quelconque, elles se portent sur les éléments voisins 
et principalement sur les cellules épidermiques dont les parois libres peuvent 
se développer plus facilement. De 1A des renflements, des radicelles et des poils. 
SCHWARZ (75, p. 149) does not consider MeEr’s results trust- 
worthy, and thinks that the checking of growth cannot cause develop- 
ment of hairs; but on the other hand that hair production goes with 
optimum growth energy (p. 155). MER repeated his experiments 
with the same results (51). SacHs (71, p. 410) found that the 
growth of roots in water is more rapid than in air. SCHWARZ (755 
Pp. 154) reports slower growth in water than in air or earth, with a 
consequent decrease of hairs. Rapidity of growth caused by optimum 
temperature, however, was not able to overcome the inhibitory effect 
of water (p. 155). The following quotation is not quite in harmony 
with his criticism of the explanation offered by Mer: “Am langsten 
werden die Wurzelhaare im feuchten Raume, und wenn das Wachs- 
thum der Wurzel durch Nutation u. s. w. besondere Hemmung 
erleidet.”’ 
JAR I. 
ied ele lon HRS. IGrowrn Pre HR. (mm.) 
S4-BRh Pe wIONS fo. Temp; ConpITION 
Water | Air Water, Air i 
eae 32.0 oe ras aa <i 
pe ee Ser 21 eo Rh eee eS 
Lt eee » 1g.0 o 0.58 iis 12° | Hairs half way down , 
a eee ee aes 5 eu 0.20 1r | One tuft 
Weeiorrne: 4:5 ss 0.19 ee 14 | No hairs 
sees ares re 7 a 0.29 19 | Hairs back to one tuft 
Le 6.0 ee 0.25 aera 18 | Doubtful hairs at top 
, AL SEA OES 15.0 i 0.65 ae 18 | Evident hairs at top 
pF eae 30.0 1.25 12 hairs . 
Average..... 16.9 a 0.71 0.46 
