330 Journal of Agricultural Research vol. vni, NO. 9 



A glance at the table shows that practically any part of the host plant 

 may contain internal sori. According to the accounts of different 

 authors, sori were found buried deep in the tissue of the host plants, 

 freeing their spores into hollow stems, or intercellular spaces, and in some 

 cases making room for the lengthening spore chains by forcing aside the 

 surrounding parenchyma cells (PL 88, B). Of course, the sori in 

 seeds had little room to expand. Fromme (3, 4) has reported odd cases 

 where the pycnium was located in the secium. The discovery of these 

 internal sori has probably been accidental in all cases, although the 

 investigators may have been looking for abnormal conditions. 



OBSERVATIONS ON THE INTERNAL TELIA OF CRONARTIUM RIBICOLA 



It will be noted that the fungus genera mentioned in Table I all 

 belong to the Puccinia and Uromyces groups. So far as the writer is 

 aware, there have been no reports of internal sori of any species of the 

 genus Cronartium. In the course of intensive investigations on fc Cro- 

 nartium ribicola Fisher, the white-pine blister rust, a striking case of 

 the development of internal telia was discovered in the petiole of Ribes 

 roezli (Regel) Coville and Britton. The plant was inoculated in July, 

 1915, and was kept in the greenhouse through the following winter. On 

 February 28, 1916, telia were found by Spaulding x on the petiole of one 

 dead leaf and of one partially dead leaf, both still remaining on the 

 plant. These petioles were killed, embedded in paraffin, and sectioned. 

 Close to the base of the leaf the pith and pericycle regions (PI. 88, A) 

 of the petiole were found to be practically stuffed with the mycelium of 

 the parasite, while farther from the leaf base there was less complete 

 destruction of the host tissue. Haustoria, which were larger and more 

 numerous than those in the leaf, suggested that the mycelium was more 

 active in the petiole than in the leaf. At intervals in the tissue of the 

 regions mentioned telia had begun to develop (Pi. 88, E). The direc- 

 tion of growth of what would normally be telial columns was very vari- 

 able, some growing toward the outside, some toward the center of the 

 petiole. Quite naturally the telia could not produce a typical telial 

 column in such cramped quarters, and the variations were such as one 

 would expect; the sori were broadened out (Pi. 88, >), the spores com- 

 pressed, and the columns where partially developed were coiled or bent 

 by the pressure on the free ends (Pi. 88, C}. Despite the distortion of 

 the columns, the spores quite closely resembled the spores from a normal 

 sorus, lacking, however, in many cases, the heavier brown wall, char- 

 acteristic of the fully developed spores of an external column. Possibly 

 the walls would have taken on the brown color as the spores matured. 

 In several of the sori, older than the others, the spores were just begin- 



1 Dr. Perley Spaulding, of the Office of Forest Pathology, supplied the material for this study, and kindly 

 furnished the data on the inoculation. 



