176 ROLAND TIIAXTER ON TIIE 



otherwise be distributed among at least four other species having spherical resting spores 

 and gi-owing upon a[)hides, namely, E. sphaerosjienua, E. occidentalis, E. Plaachonlana 

 and the foi'in under consideration. I have, it will be noticed, placed E. ferruginea as a 

 synonym of this species, although Mr. Phillips states that his species, in the opinion of 

 Mr. Cook, is a distinct form, as shown by a comparison with authentic specimens of E' 

 ApMdls. The figures and desci-iptions of E. ferruginm, however, as far as I can judge, 

 point to the ]:)resent species; and moreover the exsiccati specimens of E. AphUU.s are 

 unreliable, the two numbers that I have examined' containing in the one instance nothing 

 whatever, and in tlie other E. Fresenii, a species which cannot be confounded in any 

 way wath E. Aphklis on account of its pecuUar i-esting spores. 



Although this species {E. ApJtidis) has not, to my knowledge, been previously reported 

 from the United States it is, with the exception of E. Muscat and ])erha[)s E. GrijlU, the 

 commonest of all the Empusae; occurring abundantly in the localities above mentioned. 

 It was first called to my notice by Dr. George Dimmock who noticed it in a greenhouse 

 in Cambridge during the winter of 1886. In this situation it acted as a decided check 

 to the multiplication of the aphides, yet did not spread with sntiicient rapidity to render 

 "smoking'" in the greenhouse unnecessary. At Ivittery I have found it on numerous 

 genera of aphides and especially destructive to the forms which injure tlie hop. In one 

 case I observed a large hop vine some twenty feet high completely covered with aphides 

 which were killed off by this fungus in about two weeks; the affected hosts lieing fas- 

 tened to the under sides of the leaves, and to the younger shoots in vast numbers. The 

 destruction of colonies of Aphis by this species or by E. Fresenii seems to be the rule 

 rather than the exception, and is at least of very common occurrence. An instance of 

 the kind was called to my attention during the second week in June of the past year 

 (1887) by Mr. L. O. Howard, who showed me great quantities of aphides dying of the 

 disease on clover near the agricultural department buildings in AVashington. The prob- 

 able agency of ants in spreading these epidemics is worthy of notice as well as that of 

 night moths, especially Noctuidae, which, as well as ants, are often attracted in great 

 numbers by the sweet secretion of the aphides. 



Despite the abundance of the conidial form, I have never obtained a single specimen 

 of the i-esting spores that I have been able to discover among my material. The conidial 

 form is chiefly of interest from the pecnliar "germination" of the hyphal bodies repre- 

 sented in fig. 239, and consisting in the production, from a central cell with a highly re- 

 fractive contents, of a mass of hyphae growing from it in all directions, and subseqnently 

 giving rise to the conidiophores. This at least is the usual derivation of the mass of 

 contorted and branched hyphae which may be fonnd filling the aphides just before the 

 external appearance of the conidiophores. The number of these cells or hyphal bodies is 

 small, as may be inferi-ed from the enormous number of hyphae which each pi-oduces, 

 and their origin is a question which I have been unable to settle from actual observa- 

 tion ; although in a few cases I have found large hyphae at a less advanced stage of the 

 development of the fungus, the contents of which were collected terminally or intersti- 

 tially into rounded masses which may have represented the hyphal bodies in question. 



The conidia are noticeable from their considerable range of vai-iation, both in size and 



' iMyc. Univ. No. U)1G; Herb. M.\c. No. 708. 



