4o6 Journal of Agricultural Research voi. xviii, No. s 



the fungus, may remain dormant for considerable periods, and when 

 gemnination takes place the larval body has usually disintegrated to 

 such an extent that it is no longer recognizable. All accounts of the 

 fungus up to the present time have, therefore, been concerned mainly with 

 the resting spores, although as a matter of fact these bodies represent 

 but one phase in the rather complicated development of the organism, 

 while an equally important phase, the production of aerial conidia, has 

 usually been overlooked or at least not associated witH the chlamy- 

 dosporic condition. 



Since the resting spores are thick-walled and occur within the unbroken 

 body wall of their host, which as a rule appears to die beneath the surface 

 of the ground, and since they are freed only by the disintegration of 

 the host, it is obvious that they are not adapted to propagate the disease 

 with rapidity by carrying the fungus from insect to insect, but are rather 

 designed to enable it to survive drought and other unfavorable conditions. 



To determine the origin, nature, and function of the resting spores, a 

 number of experiments have been performed during the past two years. 



In order to induce germination, freshly collected dead larvae were placed 

 on the surface of moist sand in covered crystallizing dishes and kept at 

 room temperature in the laboratory. Three days later an external 

 fungous growth on the unbroken integument of the host was distinctly 

 visible, and after an interval of one week the latter was found upon exam- 

 ination to be composed of large numbers of conidiiferous hyphae of the 

 type illustrated in Plate 5 1 , L. The successive stages in the germination 

 of the resting spores and the development of the conidiophores are shown 

 in Plate 51, F, L, N, O. Under the stimulus of moisture and suitable 

 temperature the protoplasm of the resting spores swells, producing 

 budlike protuberances, the walls of which are in part, at least, made up of 

 the walls of the resting spores. The outgrowth soon assumes the shape 

 of a germ tube, branches freely, and becomes septate. The fully devel- 

 oped conidiophores are supplied with bottle-shaped branchlets which 

 show a tendency to group themselves verticillately around the main 

 hypha. It will be further observed that conidia are borne at the tips 

 of the bottle-shaped branchlets or sterigmata which are quite unlike the 

 resting spores from which they arose. They measure 4 to 6 by 9 to 1 1 

 microns, are elliptical in form, thin-walled, vacuolate at each pole and are 

 abjointed successively in the manner illustrated on Plate 51, P, cohering 

 after abjunction. 



The development and structure of the conidiophores as well as the 

 formation of the conidia are typical of the verticillate Hyphomycetes, of 

 which group Sorosporella should be considered a member until its perfect 

 or acigerous condition is discovered. 



The occurrence of the chlamydospores in coherent groups or aggre- 

 gations recalls a similar condition that is found in the spore balls of 



