IOWA ACADEMY OF SCTENCES 
99 
pinsapo; in Siberia on A. pichta, and in eastern North America on 
A. halsamea. It is ccmmon in the Rocr;- Mountain country on A. 
subalpina, and it has no doubt been found on other North American 
species. 
Infection. Injuries in some cases are doubtless responsible for infec- 
tion. Hartig' says: “As I have always noticed small wounds on one or 
two year old witches’ brooms close to their base — near the point, namely 
where they have developed from a bud — it may in the meantime be 
assumed, that infection occurs at such wounds, xhe mycelium of the 
fungus, which stimulates growth in a very marked manner, is perennial 
in the cortical and bast tissues of the stem, and even penetrates the cam- 
bium and the wood. Should infection occur at a part of a stem or branch 
where there are no buds capable of developing, the stimulated growth of 
the cambium induces the formation of a knob-like s\velling of wood and 
to the more vigorous development of the cortex.” 
Genetic Connection. The experiments of European investigators 
have thus lar not given very definite results. A fungus so often found, 
however, in the regions where it occurs would lead one to think that there 
must be some common teleutosporic stage. Wettstein^ found that the 
spores of P. elatinum produced Coleosporium campanulae on several spe- 
cies of Campanula. In some cases, however, his experiments were un- 
successful, and a few ncn-infected trees produced the same fungus so that 
this writer has not definitely demonstrated its connection. In a table by 
Klebahn^ on the connection of the different species of Pei'idermium the 
author expresses somm doubt in regard to the connection of this species 
with Coleosporium. Other experiments made by the same author"* seem 
to strengtnen him in his belief, nor does he consider it connected with 
Pucciniastrum epilobii Pers.* 
In recent years Melampsorella cerastii {M. caryophyllacearum (DC.) 
Schroet.) has been considered the teleuto form of Aecidium elatinum and 
Fischer quite recently has confirmed their connection,® but it has not been 
worked out in this country. The species has been collected in Wyoming 
by Nelson". ' 
This fungus differs from Melampsora in that the teleutospores are one 
celled and colorless and are produced in the cells of the epidermis. The 
uredo spores occur in pustutate scattered orange red masses and are 
enclosed in a semispherical pseudoperidium, they are ovate and ellipti- 
cal 12-16" x 22-26" with a colorless membrane. The teleutospores occur 
upon last year’s leaves, making their appearance in the spring, produc- 
ing whitish or reddish flesh-colored spots which are frequently distributed 
over the entire surface of the leaf. The teleutospores are 13-15" in 
diameter with a colorless and smooth wall. The sporidia are spherical, 
1. Sitzungs b. d. K. K. Zool. bot. Gesellsch. Wein. 40: 44. See Klebahn 
Zeitsch. f. Pflanzenk. 2: 263. 
2. Zeitsch. f. Pflanzenk. 2: 260-261. 1892. 
3. Zeitsch. f. Pflanzenk. 4 : 11. See also in this connection Wagner 
Zeitsch. f. Pflanzenk. 8: 257. 
4. Zeitsch. f. Pflanzenk. 8 : 200. 
5. Fortsetzung der entwicklungsgeschichtlichen Untersuchungen ' uber Rost- 
pilze 7-10. Ber. Schw. Bot. Gesellsch. 1902 : Heft 12. Separate Abst. Bot. Cen- 
tralbl. 89: 161. ? 
6. Crypt, of Wy. 30. 
