AMERICAN 
JOURNAL OF BOTANY 
Vol, V December, 1918 No, 10 
ENDURANCE OF EXTREME CONDITIONS AND ITS RE- 
LATION TO THE THEORY OF ADAPTATION 
W. J. V. OSTERHOUT 
Current theories lead us to expect the adaptation of plants to ex- 
treme drought or to extreme moisture, but they can hardly account for 
endurance of both extremes by the same individual. If such cases 
are found, it would seem that we must explain them by some peculi- 
arity of the protoplasm which is not the result of adaptation. This 
however raises the question whether the same sort of explanation may 
not apply in other cases whose adaptive nature is not usually regarded 
as open to question. 
Individuals which can endure extreme drought and extreme 
moisture are found among the lower plants. Some years ago the writer 
observed a similar case among the higher plants. The plant is a 
species of Tradescantia (apparently T. fluminensis Veil.) which grows 
vigorously in a saturated atmosphere, which can live submerged in 
water for some time, but which was nevertheless able to go without 
water for nearly two years: during this long period it received no 
moisture (except what could be absorbed from the air). 
Some years ago the writer observed that pieces of this plant con- 
tinued to grow when lying on a laboratory table. Curious to know 
how long they could live under these conditions, he placed some of them 
on a table before a north window without soil or other supply of mois- 
ture. Here they continued to live for nearly two years. ^ It should be 
noted that the air was not unusually moist. The laboratory was, on 
the contrary, rather dry (being situated in the third story and con- 
taining no soil or other source of moisture). The experiments were 
carried on at Berkeley, California. The following table shows the 
humidity and temperature during the greater part of the period of 
1 1 year, ii months, and 2 days. 
[The Journal for November (5: 447-506) was issued Nov. 30, 19 18.] 
507 
