Presidential Address. T. Petch. 29 
which may spread over several scales, and in Torrubiella a 
similar stroma may cover the greater part of a colony of insects, 
but the scales are usually clearly evident. In the largest group 
of scale insect fungi, however, conditions are different; in it, 
each individual fungus grows over a single insect, and, as a rule, 
not only hides it completely, but consumes the whole of it, so 
that there is no trace of the insect left within the stroma. 
Therefore, it is not surprising that the first fungi recorded as 
parasitic on scale insects belonged to the Sphaerostilbe or Nectria 
group, while the species of the larger group, Hypocrella and 
Aschersonia, were described without reference to any host, 
except the plants on which they occurred. 
The genus Aschersonia was founded by Montagne* in 1848 
for two species, supposed to be phyllogenous, one from Guiana 
and the other from Tahiti. They were pycnidial fungi, brightly 
coloured, and evidently allied to the Hypocreaceae. In 1884, 
Saccardot enumerated nine species; by the year Igoo, the 
number had increased to 26; and at the end of rg1g, there 
were 60. 
It was not discovered that species of Aschersonia were ento- 
mogenous until 1894, when Webbert{, who had studied the 
fungi and insects which occurred on Citrus in Florida, demon- 
strated that Aschersonia aleyrodis was parasitic on Aleyrodes 
cityt R. and H., Aschersonia turbinata on Ceroplastes floridensis, 
and, judging from his figures, Aschersonia cubensis on Lecanium 
hesperidum L. Webber suggested that all species of A schersonia 
would be found to be entomogenous, but his results did not 
have any immediate influence on systematic mycology. 
Hennings§ described five species of Aschersonia from Java in 
1902, and called attention to the remarkable phenomenon that 
these fungi generally occurred with various species of Lecanium, 
to which they bore so great a resemblance in form and colour 
that he considered the association should be regarded as a case 
of mimicry. Parkin||, in 1906, supported Webber’s view, and 
recorded eight gatherings of Aschersonia parasitic on Aleyrodes 
and seven gatherings on Lecanium; from the specimens left by 
him, these included A schersonia placenta, Aschersonia confluens, 
Aschersonia hypocreoidea, and Aschersonia samoensis, on Aley- 
vodes, and Aschersonia Coffeae and Aschersonia marginata on 
Lecanium. Since 1904, new species of A schersonia have generally 
been described as occurring on scale insects or Aleyrodidae; and 
at the present time, all species which are true Aschersonta in 
structure are known to be entomogenous. 
* Ann. Sci. Nat., Ser. 3, X, p. 122. ¢ Sylloge Fungorum, 111, p. 619. 
t U.S.A. Dept. Agric., Div. Veg. Physiol. and Pathol., Bull. 13 (1897). 
§ Hedwigia, xii (1902), pp. 145, 146. || Op. ctt., supra. 
