INTERNAL UREDINIA^ 
J, F, Adams 1 
(With Plate i86, Containing 2 Figures) 
The spores of the Uredinales are developed usually in sori just 
below the cuticle or epidermal layer and are liberated by early 
rupturing or by the weathering away of the overlying tissue in 
the case of some resting spores. There are deviations from this 
development in certain resting spores which are sometimes buried 
singly in the host tissues which are dependent for liberation also 
upon the weathering away of the overlying tissues. Exception to 
the usual development of sori has been reported by Wolf, Reddick, 
Edgerton, and others. 
Internal aecia were first reported by Wolf* in Puccinia angus- 
tata Peck upon Lycopus virginicus L., as appearing in the younger 
tissues of the stem or petiole, being similar in origin, structure, 
size, and form to those which are erumpent at maturity. Atkinson 
and Edgerton* have observed Nigredo Caladii ( Schw.) Arth. ( Uro- 
myces Caladii Earl.) to form internal cluster cups in Peltandra 
virginica (L.) Kunth and Reddick* has observed them in the fruits 
of barberry. 
Internal uredinia of Dicaeoma poculiforme (Jacq.) Kuntze 
{Puccinia graminis Pers.) liberating the urediniospores into the 
interior of the hollow stem of rye have been observed by Red- 
dick.* Another aberrant case has been found in the production 
of internal uredinia of Nigredo caryophyllina (Schrank.) Arthur 
(Uromyces caryophilinus Schroter) in the leaves of Dianthus 
caryophyllus L. Specimens of the rust-infected leaves were col- 
lected from plants growing in the greenhouse of the Pennsylva- 
nia State College. The leaves are succulent and are favorable 
1 Contribution from the Department of Botany, Pennsylvania State College, 
No. 4. 
2 Wolf, F. A., Internal Aecia, Mycologia, Vol. V, No. 6. 
181 
