382 BOTANICAL GAZETTE [ DECEMBER 
The toxic properties of KOH are probably largely due to 
the OH ion. It is about 94 per cent. ionized at = (Ostwald 
’86), its inhibiting point. Just what proportion of the toxic 
properties is to be attributed to the remaining 6 per cent. 
un-ionized KOH we have as yet no means of knowing. _Inas- 
much, however, as KOH is more highly ionized than HCl at the 
inhibiting point and is distinctly more toxic, we may safely con- 
clude that the OH ion is somewhat more toxic for fungi than 
ionic H. 
Ammonium hydroxid, NH ,OH; 29 (?), 57,83. This hydroxid, 
in contrast with KOH, is but slightly ionized, oe the inhibiting 
concentration, being about 8 per cent. ionized (Kohlrausch 85.) 
Its high toxic value is then doubtless due very largely to the 
un-ionized molecule. 
Like KOH, although to a less degree, it caused a marked 
stimulation of mycelial development in many cultures. It is 
worthy of note that Sterigmatocystis, which is particularly resis- 
: aie an ; 
tant to both ionic H and OH, proves quite susceptible to both 
acids and hydroxids in the molecular form. 
These results with hydroxids are not in harmony with those 
obtained by Krénig and Paul (’97) with anthrax spores,, They 
found that the bases KOH, NaOH, LiOH and NH , OF ‘disinfect 
in direct proportion to their degree of ionization,” NH,OH being 
practically non-toxic. Anthrax spores have evidently a great 
specific resistance to this agent, and perhaps even 4 general 
comparison would be unfair. Be this as it may, ammonia !> 
without doubt one of the more violent poisons for fungi, far sur 
passing the mineral acids, copper, cobalt, etc., in toxic proper 
ties, and comparing favorably with KCN. 
Data as to the effect of hydroxids on the higher plants * 
rather meager. Kahlenberg and True (’96) found Lupinus 0 
. ‘ ; plete 
survive in — KOH. As ionization is practically comple 
ij : : ‘ 0 to: 
here, Lupinus is evidently much more resistant to OH than 
