1914] HOYT—COLLOIDAL METALS 197 
out apparent injury for 5 days, except that the chloroplasts dwindled 
slightly; but on the sixth day, when the experiment was discon- 
tinued, many filaments were dead. For comparison with the above, 
two experiments were performed with Spirogyra which had grown 
TABLE II 
CULTURES OF SPIROGYRA LONGATA IN SODIUM HYDRATE SOLUTION, WITH AND WITHOUT 
COLLOIDAL GOLD AND OTHER ADDITIONS 
© eas —— substances in Cosidtiion of Duration of 
‘ = mn nm oO! 
i | Watt. per cont?.|_ mate aeoente. "plants experiment, days 
ppm, 
es 
a. 0.02 Colloid. Au, E, Eg 2,6 
90.0 
| ae 0.02 Colloid. Au, re, F 3,4 
[Plants from o.1 re) 
p.c. Crone’s 
sol., 72 days 
old] 
aes 0.01 Colloid. Au, Gp @ 
6 7 . 
ey 02 Sesto ue nna D - 
i ag Oe ee _ Pd 5 
ae 0.01 Colloid. Pt, E 5 
48.0 . 
eee 0.02 Colloid. Ag, D 
0.0135 
ee... 0.02 Colloid. Ag, Pd . 
0.009 
ee 0.02 Colloid. Ag, Gp 
9.0045 
= 7 oa 5 i eae PGE eae ee Aone oS Eg, D hd 
0 a OE ep ee ea E, Eg yi doe 
Re: 0.02 AuCl,, 100.0 Se orf, nee 
Re 0.01 AuCl, 100.0 Eg, Gp das 
ee 0.02 Colloid. Pt, E,G eA 
86.4 
ng a 0.01 Colloid. Pt, E,E fi 
86.4 
Th eine iarieipsaiay 8 
* The andi: ei? 
ay Par s. eta oie PEt 1 ee eae et an a 
tion a i 5@-9¢ P ay “i 
= the colloidal gold solution; that used in cultures ro-12b was prepared at another time. The 
Strength of the ¢. Sek 2 ; SEE SPE ieee Scneoarae ts 
tely 
t mat 
Unless otherwise noted, the material of S pirogyra used in these experiments was from the stock 
me O.2 per cent Crone’s solution for 72 days. The filaments were 
. i non-toxic water and placed in the undiluted gold solution 
(H, 56). In one case, the filaments remained in excellent condition 
two days, but a few showed injury on the third day; in the other 
“Ase, the alga remained in excellent condition one day, but on the 
