26 



2. Blossoming summer wheat was infected in the cylinder with fresh loose smut of wheat. Tn the 

 next year, from the sterilized seed, 



2,000 stalks were grown, ot which 15 per cent were smutted. 



In an equally large control of non- infected heads in the same field, 4 smutted plants appeared. 



C. INFECTION OF THE GERMINATING SEEDLINGS. 



For this infection seed of various ages was used from varieties in which no loose smut had appeared. 

 Most of the loose smut spores from 1904 were still capable of germination. They were brought to the 

 point of germination by soaking in water and then, finely divided in a dilute nutrient solution, were 

 sprayed on the plants. The germination of the seed and the spraying on the smijt spores took place at a 

 temperature of 10°. After 3 days the germinating cases with germinating seedlings were kept at a con- 

 stant temperature of 5° and, after 14 days, having developed far enough, they were transplanted into 

 open ground. 



1. Niie wheat from 1900-1901-1902-1903 and 1904 — 250 stalks of each — no smut. 



2. Ohio wheat from 1900-1901-1902-1903 and 1904 — 250 stalks of each — no smut. 



3. Lupizer wheat from 1900-1901-1902-1903 and 1904 — 250 stalks of each — no smut. 



Some comparative cases not kept in the basement, but in a warm room, at 15°-20°C. gave just the 

 same negative results'. 



4. Young seedlings of winter wheat (land wheat from Grabschen) were sprayed in the autumn of 

 1904 with smut spores of the same year, the germinating power of which had not noticeably decreased. 

 They were treated as above. 



Out of 200 plants kept over winter and matured in the next year, none were smutted. 



IV. INFECTION OF THE SUBSTRATUM. 



1. Seed of different ages was used as in III. The grains were sown in the germinating cases on 

 compost and then covered with a mixture of 2 ^arts good compost and 1 part sterilized horse manure, 

 6 cm. deep. The cases were kept a week at 6°-8°C. (being kept moderatety damp by means of repeated 

 sprinkling) and then tor 14 days in a cellar at a temperature of 5°. 



The experiment was carried through from each of the five different years, on each of the three 

 varieties named above. In all 15 cases the results were negative. 



2. Finally the same substrata were mixed in the way given above in the autumn of 1904 with 

 spores of the same year whose germinating power was still unweakened and in them were sown grains 

 of winter wheat from a, field free from smut. 



Of the plants kept over winter and developed in the next year none were smutted. 



(1) The temperature in the small rooms (Gopperstr. 4) was regulated during the night by a lighted Jet. 



