300 BOTANICAL GAZETTE [NOVEMBER 
to suppose that on this account they reacted weakly to chemotropic 
stimuli. As would be expected, the greatest turning was shown in 
B, where, when the hyphae were fairly long (200 yu) and sufficiently 
abundant, the percentage of reaction sometimes reached 40-50 
per cent. That this turning was mainly due to a negative chemo- 
tropic reaction is apparent from what follows. 
The experiments with 5 per cent cane sugar gave the best results, 
since this proportion seemed to supply the hyphae with a better 
amount of food, and also exerted a stronger positive chemotropic 
stimulus. Table V gives the results in condensed form. 
TABLE V 
RESULTS WITH 5 PER CENT CANE SUGAR 
gg! nexdhe Number of Average length Phos oe ig Total number of| Percentage of 
storey” pee nc er ag of hyphae in | mm.offilm |hyphaecounted| reaction 
surface 
=. Sead ee 116 17 162 ee 
‘- Pee Sere ee 133 25 282 = Si 
Cer ere 155 19 195 +12 
SG, 189 23 185 +32 
EAR II5 10 99 2 _ Weed! 
B AR, 139 14 150 +37 
3 ert 162 12 184 +35 
Bete 197 14 229 +55 
Cc fy f above 204 | above 18 above 253 | above —19 
1 Seale \belowror | below 5 below 280 | below —10 
Since it was clear from the experiments with turnip juice that 
the strength of the negative chemotropic stimulus was directly 
related to the length of the hyphae, the attempt was made to 
compare preparations containing hyphae of approximately equal 
length. Thus, the 4 lots of preparations in A and B roughly cor- 
‘respond. Unfortunately, the number of germ tubes averages much 
less in B, for many of the spores did not germinate, but if it were 
greater, assuming that it would be accompanied by an increased 
negative chemotropic stimulus, the final percentages in B would 
even be greater than they now are. 
It is evident from the percentages that the hyphae in every 
stage of growth in B except the youngest are subjected to much 
