300 
AMERICAN JOURNAL OF BOTANY 
[Vol. 8 
Table 2. Hydration of mixtures of gelatine j parts, agar 2 parts at 14° C. Plates 0.18 to 
o.iQ mm. in thickness; swellings given in thickness and volume 
o.oi M 
0.001 M 
0.0001 M 
Th. 
Vol. 
Th. 
Vol. 
Th. 
Vol. 
HCl 
KCl 
CaCl2 
Water 
1,200 
800 
710 
1,320 
. 880 
740 
650 
906 
870 
690 
1,010 
940 
860 
1,620 
1,300 
1,275 
920 
1,850 
1,430 
1,420 
The agar-gelatine mixtures are seen to have a higher capacity than the 
gelatine-agar, and also to react by high hydrations in greater concentration 
of potassium. 
Up to this point colloids including only tv^o of the supposed main ele- 
ments in protoplasm have been used. An agar-gelatine mixture was nov^ 
made to which was added a thousandth part of a soap which is probably 
nearly all sodium stearate. The results of the hydration swellings are given 
in table 3. 
Table 3. Hydration of plates of agar j, gelatine 2, Ivory soap 0.005 S- ^5° C. Swellings 
given in thickness and volume 
0.0 
M 
0.0002 M 
0.0001 M 
Th. 
Vol. 
Th. 
Vol. 
Th. 
Vol. 
NaCl 
890 
1,020 
2,330 
2,600 
Balanced solution 
(Na 50 : Ca i) 
810 
842 
2,460 
2,660 
CaCl2 
850 
920 
1,200 
1,374 
2,600 
2,940 
KCl 
970 
1,050 
2,750 
2,050 
HCl 
1,280 
1,460 
1,130 
1,270 
1,200 
1,250 
Water 
1,500 
1,700 
This biocolloid, representing more nearly the colloidal constitution of 
living matter, was seen to have higher hydration capacity in all salt solu- 
tions, and to have such capacity lessened in even the very dilute acid. A 
similar preparation in which the soap was pure potassium oleate gave 
results less marked as to the action of the salts, but the increase in the 
balanced solution was proportionately much greater, and the retarding 
effect in acids much greater. Ample justification exists, therefore, for a 
correction of the earlier statement as to the effect of salts of the common 
metals on biocolloids which have been found to offer many profitable 
analogies to living material. 
The correction implies that we may confidently look to these salts as 
accelerators of hydration and growth, or as increasing the water deficit of 
living matter. 
Lastly we come to the amino-acids and to water-soluble vitamine. I 
have previously pointed out in many papers that the commoner amino- 
acids, glycocoll, alanine, phenylalanine, asparagine, and histidine, which 
