ASCHERSONIA ALEYRODIS. 13 



3. On April 18, 1907, cultures were made in tap water from leaves 

 collected October 12, 1906, which had remained in the laboratory 189 days. 

 No germination took place. CZlr"::'" '""**^ 



4. On April 18, 1907, cultures were made in tap "^""^^S^niX^ 

 water from leaves collected on December 12, 1906, Fig. 4. conidiumof Ascher- 

 which had remained in the laboratory 128 days. No gftSSSftg^; SK 

 germination took place. tion at 25c.. x 1000. 



5. On April 18, 1907, germination trials were made from a culture 

 isolated December 7, 1906, which was transferred to potato on January 14, 

 1907, and had not entirely dried out. A few spores germinated. 



CULTURES. 



Pure cultures of Aschersonia aleyrodis were first obtained in January, 

 1907. On December 7, 1906, petri dishes of neutral 5 per cent, glucose agar 

 were poured. These were made by introducing into the melted agar a 

 platinum loop, that had been thrust several times into a test-tube containing 

 spores from several stromata shaken up in sterile water. In the first dilu- 

 tion, on January 5 (29 days), at a temperature of 15 to 25 C., minute 

 fungus mycelia appeared, yellow in the center, with a fringe of delicate 

 white hyphae projecting outward. On January 8 .(32 days), the largest 

 of these had turned red in color. They were raised, hemispherical, and 

 had the upper surface dotted with little white lumps. Larger stromata were 

 2 to 4 mm. in diameter. On January 15 (39 days) the stromata were 5 

 to 7 mm. broad, with a wide fringe of straight hyphae projecting outward 

 over the agar. The stroma by this time contained pycnidial cavities with 

 spores (Plate I, Fig. 20). 



On April 10, 1907, this fungus was again isolated. Leaves were picked 

 at Orlando, on April 6. Pustules were broken up in water in a watch-glass, 

 and a dilution set of three petri dishes A, B and C, was poured with agar 

 (1 per cent, normal acid to phenolphthalein) , to which 5 per cent, glucose 

 sugar had been added. Petri dish A was overrun with bacteria and quick- 

 growing fungi. Petri dish B contained, on April 26 (16 days), about 50 

 centers of growth just beginning, and a few bacteria. Petri dish C, on 

 April 26 (16 days), contained no visible growth. On May 11 (31 days), 

 C contained a fine growth of 11 mycelia, which probably first showed a few 

 clays before. No further record was kept. 



On September 23, 1907, this fungus was isolated for the third time in 

 petri dish cultures A, B and C. Four or five small pustules were shaken 

 up in 7 cc. of water until it became milky in appearance. Five loopfuls w r ere 

 washed into A, etc. A was contaminated with other fungi, C developed one 

 mycelium of A. alcyrodis, and one of another fungus. Petri dish B devel- 

 oped a pure culture as follows: On October 8 (15 days), one point of 

 growth was just appearing. On October 18, there were four mycelia, five 

 to six mm. in diameter, with rings of reddish pycnidia ; and seven others 

 just starting. On October 28 (35 days), twenty very red pustules with 

 abundant spores and light gray fringes of outgrowing hyphae had de- 

 veloped. 



From these isolation tests, it appears that on 5-10 per cent, glucose agar 

 in the laboratory, it requires from 30-40 days for the fungus to mature a 

 pustule and produce pycnidia. This time corresponds somewhat closely 

 to the time for the fungus to develop upon larvae of Ale\rodc$ citri, as 



