I2 BOTANICAL GAZETTE : [JANUARY 
its usual persistence as a distinct membrane than by its ontogenetic 
history, though he states (1b, p. 386) that some laterally inflated 
toward hyphae led him to believe that this indicates a differentiation 
pseudoparenchymatous tissue. SCOFIELD (15, p. 533) does not con- 
sider the veil in P. ravenelii to be a differentiated organic structure, 
but a remnant of the tissues of the young fruit body. Consequently 
he follows FiscHER in placing the species in the genus [thyphallus. 
It appears that LLoyp (9, p. 327) treats the indusium of Dictyo- 
phora and the veil of Ithyphallus, even the very thin and fragile 
veil of IJ. impudicus, as homologous structures, probably without 
a consideration of their different origin and ontogenetic history, 
since he thinks ‘‘the only difference is in the degree of development 
of the veil.” On this basis he would discard the genus Dictyophora, 
and place all three of the species in question here in the genus 
llus. | 
There are two methods by which the relative value of these 
structures (the “‘veil”’ and indusium) in showing generic relation- 
ship may be considered: (1) by their morphology, that is, their 
form, structure, and position relative to other organs of the plants; 
and (2) by their origin and differentiation in the individuals, or 
in other words their ontogenetic history. According to the first, 
it is not sufficient that we should compare these structures after the 
expansion of the plant. Some of the present confusion probably 
can be traced to observations made only at this stage of develop- 
ment. Observations and comparisons should also be made before 
the elongation of the stipe has so disarranged the parts as to make 
impossible a careful comparative study of these structures in their 
normal position. For the purpose of this study fruit bodies of the 
three species (I. impudicus, P. ravenelii, and D. duplicata) were 
selected a short time before complete maturity, but after complete 
differentiation of the parts had taken place, and only a com- 
paratively short time before the period of elongation. Micro- 
tome sections were made of these, longitudinally at the upper and 
lower ends of the “‘egg,”’ and transversely as well as longitudinally 
in the middle region. These sections included the volva, pileus, 
and one side of the stipe (to or near the middle), and of course the 
tissues in question between the pileus and stipe, and the base of 
