1909] 



DACHNOWSKI—BOG TOXINS 



393 



seedlings were used in any experiment. It should be observed also 

 that the seedlings were selected individuals out of a large number of 

 plants. The corks used were- previously sterilized and paraffined. 

 Growth was measured by transpiration and the green and dry weight 

 of plants. The cultures stood side by side in the university green- 

 house in diffused light. The weekly atmometer readings varied 

 between 176 and i86 cc . Below are given toxicity figures for bog 

 water collected at two periods. Column I gives data for bog water 

 collected September 12, 1908, nearly at the end of one of the most 

 severe droughts that have been experienced in Ohio; the bog water 

 for column II was brought to the laboratory October 16, soon after 

 the first rains. The evidence derived from similar experiments with 

 bog water collected at intervals of one month during the year is 

 omitted, showing, as it does, considerable repetition. It should be 

 noted, however, that the variation in the range of results for the 

 seasons is considerable. 



TABLE I 



Adsorption of bog toxins by quartz sand 



Solution 



Corresponding 



place ON 



CCRVE 



Total transpiration tor 15 



DAYS, Df GRAMS 



I 

 2. 



3 



4 



5 

 6 



7 

 8 



9 

 10 



Distilled water 400°° 



Bog water 400" untreated. . . 



Bog water 400^ boiled 



Bog water 400^+ 25 cc Si0 2 . 

 Bog water 4oocc + 50 cc Si0 2 . 

 Bog water 4 oo« + 75" Si0 2 . 

 f>og water 400" + ioo« SiC> 2 

 Jog water 400" + I25 cc Si0 2 

 oog water 400" + i 50 cc Si0 2 

 tfog water 400^4. 200 cc SiQ 2 



A 



B 



B' 



C 



D 



E 



F 



G 



H 



K 



I. Sept. 12 



II. Oct. 16 



7-5° 

 10.26 



22.70 

 39.28 



48-73 



18.60 



7-5° 

 14.90 



54-22 



25-50 



18.17 



13 83 



13-50 



12.87 



12.55 



fig 



The 



^wth-rate in terms cf transpiration is indicated on the axis of ordi- 

 ate s, and the progressive addition of quartz to bog water is shown on 



the 



axj s of abscissas. 



— — -^ m^ ^-» * f w 



before taking up the facts brought out in this series of experiments, 



anothe 



tore 



r 



part of the investigation must be mentioned here. 



The 



going observations suggested the query whether results obtained 

 sons of varying quality, fineness, and adsorbing surface would 



