1908] '  DACHNOWSKI—TOXIC PROPERTY OF BOGS 133 
dishes (9.5% 4°™) containing 100°¢ of bog water. Cultures were 
prepared, containing respectively the untreated bog water from each 
zone and spring water. The gemmae were allowed to float on the 
surface of the solutions. An additional series of test conditions was 
arranged at the same time from the bog water of each zone variously 
treated. In the table given below, culture medium no. 3 is bog water 
aerated daily by means of a rubber bulb; no. 4 is prepared by mixing 
with the bog water dry calcium carbonate and then filtering off the 
solution; no. 5 is treated by shaking the bog water with carbon 
(lampblack) and then filtering off the solution; no. 6 is a culture 
medium obtained by growing in distilled water in battery jars a set of 
representative plants from each zone. The attempt is made here to 
simulate undrained bog conditions and to test the water for excretions 
of roots. To discover whether the effects of poisons were also mani- 
fest in the bog substratum, a relatively concentrated aqueous extract 
Was prepared. Quantities of the subsoil from each station were 
— from a ‘layer 30°" below the surface vegetation and dried 
Mm an Oven at a temperature varying between 52° and 60° C. One 
gram of the material was then mixed with 100° of distilled water 
ane left standing for several days. The soil solution thus obtained 
as used as culture medium no. 1. There were thus produced six 
conditions for each zone in which it was possible to test the bog soils, 
te excretions of bog plants, the effect of aeration, and toxic ingredients 
: eee Water, The following Table I shows the results of growth 
length of marchantia gemmae during a period of twelve and twenty- 
five days. 
bs : hep be noticed that the gemmae made scarcely any growth in the 
eae while in the untreated bog water a fairly good wee 
Evidence P inhibiting action of these solutions is plainly marked. 
the first me pe _ further obtained from a microscopic study. ssi 
ten days es . six days the sete made some growth, but - 
tWo opposi 63 ps spe ceased. Only in the untreated bog water the 
e Posite growing points of the gemmae were thrifty in appearance. 
the iat er to narrow threadlike filaments, which > 
solutions sete day began to broaden at the tip. In 
Were hd 5 th Was greatly increased after treatment. Exceptions 
nly when the bog water used was collected just following 
