133 



exceeding" certain dinicnsionj 



that every small di-op of lo miHeorams weight will contain 

 thousands. Using such a concentrated spore sediment as a 

 solvent for grains of sugar it is not difficult to prepare a fly- 

 food such that if the spores survive ily digestion it is easy to 

 test their subsequent germination. As a matter of fact, some 

 flies exercise a considerable choice in the size of the solid par- 

 ticles that they ingest. They are supplied with a sifting ap- 

 paratus bv the aid of which they can exclude particles 



It appears, however, that the 



Fig. 5. PLxpIanation of the figures of 

 aerial conidia of Thielaviopsis. 



Eleven spores germinating, and eight 

 that have not yet started to germinate. 

 ". a chain of six aerial conidia as they oc- 

 cur when attached to the parent mycelium. 

 h. e. two spores sliowing some of the ex- 

 tremes of size and form; d, a spore that 

 has swollen and become somewhat spherical 

 preparatory to germination ; e. a spore that 

 has become spherical and started to send 

 forth mycelium at the left hand side; /, 

 three spores a stage farther advanced than 

 that at e, these three spores being part of 

 the same chain as that marked d. but all 

 now separated; g, two spores still farther 

 advanced than those at /, one of them hav- 

 ing started to branch at a much earlier 

 stage than is usual with this species; h, h, 

 spore whose hypha has one septum: i. i, 

 spore whose hypha has two septa: ;, three 

 spores still attached to each other that have 

 nevertheless germinated. 



The spores a, b. c, have been mounted 

 in water and drawn at once. The remain- 

 ing spores have been passed through the 

 fly Eristalis punctidatus. a common Syrphid 

 fly ,and afterward germinated in pineapple 

 juice. The passage through the fly makes 

 no difference in the germination of the 

 spores. The spores a to e would, if placed 

 in pineapple juice, germinate in precisely 

 the same manner. 



macrospore of Tliiclaz'iopsis is somewhat below these dimen- 

 sions. At any rate, tlie spores are mgested by various com- 

 mon species of flies belonging to the Muscidae, Sarcophagidae 

 and Syrphidae. All the species 1 have tried are such as nor- 

 mally search out and prefer saccharine food. These take in 

 the Thielaviopsis spores with sugar solutions artificiallv pre- 

 pared as described, and the spores pass through the insects 

 with little if any apparent alteration. From one to a dozen 

 or more spores are to be found in each portion of excrement 



