18 FUNGI PARASITIC UPON AI.EYRODES CITRI. 



servations will reveal its presence on other Aleyrodidae native to the woods 

 of Florida. 



COMPARISON OF ASCHERSONIA FLAVO-CITRINA WITH A. ALEYRODIS. 



The two species are very much alike in their general appearance, and 

 also approach each other closely in the measurements of their structural 

 parts. The most evident distinction is in the color. A. aleyrodis is usually 

 red or pink, while A. flavo-citrina is yellow and never contains any reddish 

 pigment. The stromata of A. aleyrodis, under similar conditions, average 

 less in diameter, and the pycnidial cavities are usually more sunken than 

 in A. flavo-citrina. The spores of A. aleyrodis also average a little smaller 

 than those of A. flavo-citrina. Measurements of Florida specimens show 

 that the spores of A. aleyrodis are about 9 14X2 3 microns, while those 

 of A. flavo-citrina measure about 12 15X2 3 microns. Cultures of these 

 two Aschersonias on similar culture media, under similar conditions, showed 

 them to be distinct forms. 



CULTURES. 



Soon after the discovery of A. flavo-citrina on Aleyrodcs citri, attempts 

 were made by the writer to produce cultures of this fungus on ordinary 

 culture media. Attempts to isolate Aschersonia aleyrodis on neutral pep- 

 tonized agar had been made without success. The beneficial effect of the 

 addition of sugar on the germination of the spores in hanging drops had 

 been noticed. On the addition of 10 per cent, glucose to the agar, petri dish 

 cultures of A. flavo-citrina were successfully grown. The growth on 10 

 per cent, glucose agar, poured on September 14, 190f>, at a temperature of 

 about 28 to 30 C., was as follows: 



On October 2 (18 days) small, whitish delicate-fringed colonies ap- 

 peared, just visible to the unaided eye. On October 11 (25 days), a distinct 

 elevated stroma had formed, waxy and pale, with a yellow center contain- 

 ing pycnidia with spores. Surrounding this was a white fringe of outgrow- 

 ing mycelium. These stromata became 2 to (> millimeters in diameter, and 

 closely resembled the stromata growing naturally on leaves bearing larvae 

 (Plate III, Fig. 2G). Later cultures grown on the same medium bore 

 stromata 2~> millimeters in diameter, indicating that the size of any individual 

 stroma depends on the amount of the medium taken, and the length of time 

 before it is dried out (Plate III, Fig. 27). The fungus was then transferred 

 to test-tubes containing other media. Cultures were obtained on sterilized 

 SWeel potato. Irish potato, hread and Her. The most luxuriant growth was 

 obtained on sweet potato plugs, this being probably due to the presence of 

 BUgar in that medium ( I 'late IV. Figs. 88, -.".' and 30). 



The progress of the fungus on the various media was as follows: 

 On sweet potato pings, transferred from petri dish culture by inserting a 

 platinum needle into a spore mass, tin-re was no evident growth in three 

 days. In six days, numerous small white points appeared along the scratch 

 made- by the needle. In fourteen days, stromata > mm. in diameter, and 

 turning yellow, were formed. In twenty days these had heroine typical 



