210 
TENTH REPORT. 
(7). The variety of material cited seems to offer sufficient proof that 
(a) toxicity is a factor in certain soil problems; 
(b) the inhibiting factors of bog conditions are in part due 
to the presence of injurious, toxic, water-soluble sub- 
stances — reactions of the plants themselves; 
(c) these substances are formed in the absence of O 2 and 
probably retard oxidation in the tissues as well as transpira- 
tion, thus causing stunting and even death; 
(d) such toxicity can be corrected by various methods; 
(e) an undrained peat substration must therefore necessarily 
cause a different succession of plants than a drained 
habitat. 
Botanical Laboratory, Ohio State University. 
EXPLANATION OF PLATES. 
Half-liter jars of the Mason pattern were used, and prepared in the con- 
ventional way. The seeds were germinated in sawdust. Transplanting 
was done when the plants had attained a height of 5-6 cm. The culture 
media used were prepared as follows: 
Solution 1 was made by taking quantities of the subsoil a foot below' the 
surface vegetation and drying it in an oven at a temperature varying be- 
tween 52° and 60°C. One gram of this was mixed with 100 cc. of dis- 
tilled water. 
Solution 2 was bog water untreated. 
Solution 3 is bog water aerated daily by means of a rubber bulb. 
Solution 4 was prepared by mixing into the bog water dry calcium car- 
bonate and then filtering off the solution. 
Solution 5 was treated by shaking the bog water with carbon (lamp- 
black), and then filtering off the solution. 
Solution 6 was obtained from a set of representative bog plants. These 
were grown in distilled water, in battery jars and i his water was then 
used as a culture medium. 
