1905] TRUE & OGLEVEE—TOXIC ACTION OF POISONS 7 
solids present may be responsible for the differences noted. In 
some degree, also, slight differences in handling during the experi- 
ment and also individual differences in the roots produce slight, 
uncontrolled effects. 
Copper sulfate. 
A greater number of experiments were made with copper sulfate 
than with any other substance. This has an added interest because 
of NAGELI’s (2, p. 23) experiments with Spirogyra in extremely 
dilute solution. NAcELr found that distilled water prepared by means 
of a copper still may contain enough metal to produce fatal results 
with Spirogyra. The remedy proposed as a laboratory expedient 
for making water thus prepared fit for use was to put finely divided 
insoluble bodies into the water. The results obtained with copper 
sulfate follow. Although there is considerable repetition and some 
experiments are not completely carried out, it seems desirable to 
present all the evidence, showing as it does the range of variation 
in the results: 
TABLE II. 
COPPER SULFATE, 
I gram-molecule Growth in 24 hrs. Growth in 7o hrs. 
Jury 8 
ESO TET i ee wick eet « viny bo on nti ae 2.9mm Dead 
aie gril et iid euler Be Rleaay oes SOAS chapel pt ate 2.0 on 
aA cs NOs ks ches ered See  Waee mera EN, e 
#552 TORS + SAMs ies Sen kes Shes eh eee Fs 4.0 * 
Thtetitied! ‘writers. cas nd oe esa em eee eeese ee 12.0 17.9mm 
JULY 10 
50,000 li Ee cd areude ek GREE ME eran ie eee 1.0 Dead 
50,000 ters sand 9 0s & de wae dren ened 14.0 28.omm 
PENS OEE, os cna ec ened sass Ween o ese ce eee 72. 28.0 
Sa ert sane be Soca ak eee sa Ae 16.0 32.0 
JuLy 13 Growth in 48 hrs 
35) Ee Pe org sae ek carts tional owne 98 Res I.0 Dead 
AS Me MeL S 4 SANG, C5. yds ae Stee sence we eee 7.0 I2.9mm 
RIO tenis sl PISS ak face eles 4s ae ERAS Os 8 2:0 Dead 
AED CON TE 1- SAL Groh cit Gia, eee ont aia ems 5.0 g.omm 
MN I I 5 12 Awan ace sb ease eee 2.0 Dead 
50,000 Boies lis Mle ates ar oldie eccre oalle we eee rp ee, 17.9mm 
DMI URN a ei lV aswiieie s Kirk ga ew nwa ow 10.0 13.0 
istilled tics Se PMMA ig re Att Shona aK a, sive e 8.0 15.0 
