AGf~ICULTURAL RESEARCH, PUSA.

FlLTERABLE 'VIRUSES 465
of rabbits-will survive for less time than] certain
ordinary bacteria.. It is essential that the glycerol he
pure and free from mineral acids and sulphates.
(The filterable viruses are very readily destroyed
by heat and antiseptics, but may survive outside the
body for considexable periods of time, and can also
rcsist desiccation.)
7. When lesions occurring in filterable virus diseases
are examined histologically there aTe frequently fonnd
within the cell nucleus, or the cytoplasm, peculiar
structures which may be of two types-namely:
(1) " Elementary bodies";
(2) " Inclusion bodies."
" Elemcntary bodies" appear to represent the actual
virus, and these arc exemplified by the "Paschen
corpuselcs " which are seen in smallpox and vaccinia
lesions and which may be demonstrated in the vesicle
Huid of early vaecinia in calves. They arc smallroulld
coccus-like hodies, about O·25,u. in size. Similar bodies
have been founel in varicella, while they arc
demonstrable in the lesions of psittacosis, molluscum
eontagiosum, ectromelia and fowl-pox. They can be
demonstrated by Castaneda's stain (p. 176) and by
prolonged staining in Giemsa's solution, when they
appear red or purplish. By comparison wit.h photographs
taken with ultra-violet. light (Barnard), the
effect of staining is to make them appeal' larger.
The work of Ledingham on the Paschen corpnscles
of vaccinia, and of Bedson on the elementa.l'Y bodies of
psitta.cosis, indicate that these bodies reprcsent actual
virus particles.
" Inclusion bodies" may be :
(a) Cytoplasmic-e.g. the Negri bodies which are
found in the ganglion cells of the central
nervous system in rabies, the Gual'nieri bodies
of smallpox and the Bollinger bodies of fowlpox.
These inclusion hodieR are acidophile in
nature, and with Mann's methyl-blue-eosin 1 or
1 See H .• J. Conn, Biological Stains" 2nd edit., H)ZO, p. 112,
.j n_