132 



chains of spores no nivcelial wall was to be seen. In fact, it 

 appeared that the spores had formed merely by the seg-menta- 

 tion of aerial mycehum, which, however, originated internally 

 from other mycelium. For these spores the name aerial 

 conidia is at once descriptive and noncommittal. It is evi- 

 dent to me from my studies of this fungus that its various 

 forms and activities are as yet but imperfectly understood. 



The further history of the aerial conidia is as follows: In 

 the course of twenty-four hours the white coloration due to 

 the mass of these spores becomes darker owing to the slight 

 darkening of the spores themselves, but more particularly to 

 the growth of ordmary macrospores from the mycelium below. 

 The chains of aerial conodia placed in water no longer rem i.i 

 intact. Ihev break up almost without exception. The spores 

 have the dimensions shown in the adjacent table. If 

 they are placed in proper nutritive fluids they 

 germinate promptly. The first indications of 

 germination is a change in the form of the spore, 

 by which it becomes nearly spherical. It then 

 germinates from what was the side or the end of 

 the spore, apparently more often the side. It is 

 often diflicult to say what part of the spore pro- 

 duced the hypha, so perfectly round do they be- 

 come before germination. In the course of 12-15 

 hours the mycelium, which is colorless and more 

 or less regular in form and direction up to this 

 8.4 5.4 stage, may be 25 times as long as the swollen spore 

 is wide. The mycelium is septate, the cells being 

 5-15 times as long as wide, and each hypha containing several 

 such cells. I'p to this stage the hyphae are little, if any, 

 branched. Tlie present description is made from the 

 germination of spores that had passed through the intes- 

 tinal canal of Eristalis puucfulatus, ]\Iacq., the commonest 

 Syrphid fly around Honolulu, but there is no reason to sup- 

 pose that the germination of spores that had passed through 

 this insect w^ould present any peculiarities worth mention. 



THIELAVIOPSIS AND FLIES. 



If some of the sooty black mass be taken from a pineapple and 

 be forced gently through the meshes of the finest miller's silk 

 sieve, that is, a sieve of about 100 microns square (1-250 inch) 

 in the clear, the macrospores may be separated out in consid- 

 erable purity. By accumulating these spores in a watch glass 

 of water, and assembling them with the aid of sedimentation 

 and rotation, it is very easy to procure them in such numbers: 



