EXPERIMENT STATION BULLETINS. 649 



were placed in a closed tin vessel and with the checks were placed in a 

 dark corner of the room. After seven days, examination showed no dif- 

 ference excepting those in the light developed aerial mycelium. This 

 was absent in the tubes which were covered. 



It has been mentioned above (page 17) that in the experiment dealing 

 with the growth of the organism on various media, Series 1, was placed 

 in the greenhouse under the plants which were severally attacked by the 

 disease. Series 2 was in the ice box. Series 4 on shelf in the laboratory 

 window and Series 5 in laboratory but in diffused light. The results in- 

 dicated that these series were indistinguishable in their development. 



Eelation to Oxygen: 



It was mentioned also (page 17) that the experiment was carried on 

 in triplicate, one of which was sealed. When these were examined it 

 seemed that some tubes showed exactly similar development to the un- 

 sealed while others of the sealed tubes indicated a very scanty growth. 

 This incongruity was explained when it was found that every "sealed" 

 tube which appeared similar to the unsealed tubes had developed small 

 pin holes in the sealing wax. While conclusions can hardly be drawn 

 from such an accident it may be well to note that there was no grada- 

 tion from the sealed to the unsealed; the pin holes evidently serving as 

 efficiently for the air supply or circulation as the larger and loose cot- 

 ton plugs. In the tubes which were competely sealed, slight develop- 

 ment was evident, but no pycnidia were observed. 



D issemina Hon : 



The connection of the organism to some ascomycete is commonly postu- 

 lated. This postulate receives support from analogy with other Sep- 

 torias (Klebahn, 1908). Potebnia (1910, p. 167) has expressed the opin- 

 ion that the viability of conidia of a Septoria after wintering indicates 

 loss of the ascomycetous stage. This certainly finds no substantiation 

 in other ascomycetous life cycles, and is not sufficient ground for elimi- 

 nation of the possibility of the possession of an ascus stage. Attempts 

 were made to find this hypothetical ascomycetous form, but were un- 

 successful. Affected leaves were buried at various depths in the ground, 

 November, 191.3.'^ A careful examination of this material in March, 

 April, and May, 1914, failed to reveal an ascus form. Old, diseased 

 stems from the previous year's crop were examined with negative re- 

 sults. Dried pure cultures on cornmeal were examined, revealing no 

 perfect stage. 



It is noteworthy that on the wintered stems and leaves a remarkable 

 increase in the fungus thallus had occurred, forming a conspicuous 

 stroma, in which the pycnidia were immersed, without however, the loss 

 of identity of the pycnidial walls. Statements, without citation of ex- 

 perimental work, have been made that the fungus lives over on the 

 Irash, (Cook, 1913, Stuckey, 191.5), and on greenhouse frames and sashes 

 (Giissow, 1908). Spores from pycnidia found upon wintered over vines 

 were put in Van Tieghem cells. Ten per cent of the spores showed ac- 

 tive germination. It cannot be definitely affirmed that this is the only 



'Two pieces of wire mesh (4 mm.) 12 Inches square were used for this purpose. These were 

 lined with a thin layer of cotton which was thinly covered with fine sand. Infected leaves 

 and stems showing abundant pycnidia were placed between these wires. This was submerged 

 in a sandy loam soil near the greenhouse at an angle of 30° with the surface of the soil, 

 the top slightly projecting, exposing about 3 inches of the wires. 



