568 KUNKEL: ORANGE RUSTS OF RUBUS 
the teleuto-stage of Gymnoconia has not yet been found. Lage- 
heim’s (8) suggestion, ‘(dass das Caeoma sich reproduciren kann,” 
is interesting in this connection. He writes: ‘‘Aus mehreren 
Griinden scheint es mir nun nicht unméglich, dass die Aecidien 
unserer Gymnoconia sich zu reproduciren vermégen. Wahrend 
dieselben namlich an vielen Orten des europiischen und asiatischen 
Russlands, im nérdlichen, mittleren und siidlichen Schweden-und 
bei Miinchen gefunden worden sind, so sind die dazu gehérenden 
Teleutosporen (in Europa) nur bei Kuikkjokk im Schwedisch- 
Lappland, bei St. Petersburg und Moskau beobachtet worden.” 
The orange rust of Europe seems to be of no economic importance 
and so far as the writer knows has not been found on cultivated 
blackberries or raspberries. This suggests that the rust so often 
reported as doing great damage to cultivated blackberries and 
raspberries in the United States is the short-cycled form. The 
writer has twice collected the orange rust on cultivated black- 
berries and in both cases it proved to be Caeoma nitens. It 
would be an interesting experiment to determine whether Gymno- 
conia is capable of infecting our cultivated blackberries and rasp~ 
berries. This and many other experiments that suggest them- 
selves must be left for future studies. Questions as to which of 
the two forms is the more primitive and as to what environmental 
conditions may have led to the development of two rusts with 
such different life histories and yet so much alike morphologically 
must at present be left unanswered. Both forms deserve further 
study. 
SUMMARY 
1. There are two forms of the orange rust on the blackberries 
of the United States. One is the Caeoma-stage of Gymnoconta 
interstitialis (Schlecht.) Lagerh.; the other is a short-cycled 
rust with a life history like the Endophyllums as described-by 
Arthur (1). 
2. The two rusts are morphologically alike in their Caeoma- 
stage though so different in their life histories. 
3. The germination of the Caecoma spores is in the one case 
(Cacoma nitens) teleutoid, in the ‘other (Gymnoconia interstitialis) 
it 1s just as typically aecidioid. 
4. It is impossible at present to determine in the numerous 
references to orange rust of blackberries which form was under 
