452 SECTIONAL TRANSACTIONS.—D. 
to condense around the nuclei, and by the time the next nuclear division is 
completed the cytoplasmic division is also complete; thus are formed about 
4,000 rounded cells trom wiich, by two further divisions, some 16,000 young 
spores are produced. ‘The central spores begin to enlarge, their cytoplasm 
becomes vacuolated, and refringent spherules appear, each lyimg in a vacuole, 
until ten to sixteen are present. ‘he spherules have been previously mistaken 
for sporules, as many of them exhibit, in iron-hematoxylin preparations, a more 
deeply staining central portion of denser material or of different composition, 
which, however, is not a nucleus. The thin film over the pore of the sporangium 
ruptures, and the ripe spores issue; the majority of them escape in the nasal 
secretion, but others become distributed in the tissue, where the stages of trans- 
formation from spore to trophic phase have been met with. 
It is suggested that the nearest relatives of Rhinosporidium are not the 
Sporozoa, but the lower fungi (Phycomycetes), such as the Chytridine. 
19, Dr. J. W. Hestor Harrison.—Polyhedral Disease in the 
Vapourer Moths of the Genus Orgyia. 
Certain Lepidoptera, in particular the Liparide, are subject to diseases 
known as polyhedral diseases, not up to the present recorded from the British 
Islands. However, an epidemic, quite typical in its symptoms, broke out in a 
series of cultures of Orgyia antiqua reared for genetical research from wild 
Aberdeenshire ova. In these batches the larve attacked succumbed for the 
most part just before reaching full growth, but others managed to pupate 
before doing so. Only rarely were imagines reared from diseased broods. 
Affected caterpillars, immediately after death, disintegrated into a brownish 
liquid having a faint, nutty, and not unpleasant smell. Microscopical examina- 
tion showed this to be crowded with bodies roughiy polyhedral or crystalline 
in appearance, which originated within the nuclei of blood, fat, tracheal and 
other cells. 
Attempts made to infect the larve of Gipsy and other moths met with but 
little success, although many Orgyie forms proved very susceptible, and from 
them passage infections were carried out. Clearly, unless the Italian race of 
Liparis dispar employed is immune, the disease is not identical with that 
attacking the Gipsy Moth. 
In the successful experiments certain hybrids and races were more resistive 
than others, and the males more so than the females. This immunity of the 
male is more apparent than real, and depends on the fact that the male Orgyia 
larva has one less instar than the female. 
Evidence was secured proving that the disease could be transmitted through 
the egg. 
20. Mr. A. D. Peacocxk.—Parthenogenesis in Saw flies. 
Revised list of parthenogenetic species; recent additions to list. Partheno- 
genetic condition within the group and the problems arising therefrom—e.g. 
thelyotoky and arrhenotoky within the same genus, deuterotoky. New observa- 
tions on the breeding habits and their significance in relation to sex-ratio ; 
dechandry and adechandry, impotence. Sex-change experiments (1) by dieting © 
larve with chemically treated food; (2) by X-ray, electrical, and chemical 
treatment of eggs. Species used : Pteronidea ribesii, facultatively arrhenotokous, 
occasionally deuterotokous; Pristiphora pallipes (in which the male is exces- i 
sively rare), thelyotokous; Atlantis pallipes, obligatory thelyotokous. Brief | 
reference to gametogenesis. # 
u 
21. Mr. BE. R. Spryver.—The Evolution of Aphids with Complex Life- 
cycles. 
Researches upon the Larch Chermes (Cnaphalodes strobilobius Kalt) have } 
brought to light certain processes of development relating to regular increase 
of one type of individual over another in successive generations, independently 
of environmental conditions, and to a regular alternation of form controlled by _ 
an internal mechanism. From these principles it is possible to arrange the 
existing species of Chermesine in an evolutional series, starting from the 
earliest period at which parthenogenesis correlated with apterism resulted in a 
