1913] KNIGHT & CROCKER—TOXICITY OF SMOKE 343 
epicotyl of the pea, if less than 1 cm. tall, is due to the joint action 
of autonomic nutation and diageotropism; but, if taller than 1 cm., 
it is due to diageotropism alone. It should be mentioned in this 
connection that NeLyusow worked mainly with taller epicotyls, 
which probably accounts for the autonomic nutations escaping 
detection by his careful methods. 
b) The swelling 
The increased diameter or swelling of a plant organ in the 
presence of poisons is apparently a rather commonly observed 
phenomenon. Cook and TAUBENHAUS (5) observed that in proper 
concentration of tannin the mycelia of various fungi tend to become 
short, thick, and much septate. GRoOTTIAN (12) finds that anaes- 
thetics, especially chloroform, produce a swelling in the root just 
back of the tip, with constrictions above and below. Né&meEc (27) 
finds that chloral, ether, benzine, benzene, and alcohol vapors have 
a similar effect. 
The anatomical structures of the swollen zone, along with the 
physiological condition causing the peculiar structure, has been a 
subject of some comment. As RICHTER (35) has stated, the 
swollen region shows an abundant development of collenchyma, 
also numerous rifts more or less lined with cork. RiIcHTER (36) 
has related the swollen condition and the development of rifts to 
excessive osmotic pressure induced by the poisons. So far as his 
cited articles are concerned, there is no evidence that he has made 
any measurements of osmotic pressures. His conclusions are 
based on two lines of indirect evidence. First, many observers have 
found an increase in osmotically active substances in plants grown 
in an atmosphere bearing poisons. JOHANNSEN has shown that 
soluble sugars increase in plants in the presence of ether and other 
anaesthetics. PRIANISCHNIKOW (29) has shown that etiolated 
lupine seedlings grown in laboratory air have a much greater 
amount of asparagin than those grown in pure air. The following 
table (p. 344) gives the difference, in percentage, wet weight, of 
asparagin in 12-day seedlings in pure air and laboratory air. 
Grare (10) has shown that soluble sugars accumulate in plant 
- organs at the expense of starch in an atmosphere bearing formalde- 
