462 SECTIONAL TRANSACTIONS.—I. 
Dr. C. H. ANDREWES.—Eatrinsie Origin of Viruses. 
Since it is hard to define a living thing it is well to leave aside for the present the 
question of whether viruses are alive or dead. It is more profitable to discuss whether 
they have an intrinsic origin from the affected cell or whether they reach it from 
outside. This question is discussed from three points of view with reference to the 
viruses of herpes simplex and the filterable fowl tumours. 
(i) The epidemiological argument that these viruses must have an intrinsic origin 
because they appear to arise in no relation with other diseased individuals is shown to 
be fallacious ; such a state of affairs is well known to occur in the field of bacteriology. 
(ii) The viruses discussed are not confined to the limits of one species. Herpes is 
transmissible to rabbits and other animals; the virus of Fujinami’s fowl sarcoma to 
ducks; the virus of Rous’ No. 1 fowl sarcoma to pheasants. These viruses are 
antigenic and therefore presumably proteins. It is hard to believe that a human 
protein can be multiplied by rabbits or a fowl protein by ducks. Yet this is what 
would have to be believed if the viruses were of intrinsic origin. 
(iii) Human beings with herpes and birds with fowl tumours develop antibodies to 
the infecting viruses. It is contrary to all our knowledge of immunology to believe 
that the body can make antibodies to products of its own abnormal metabolism, such 
as viruses must be if they originate within the body. 
Mr. J. E. Barnarp, F.R.S.—Mieroscopic Methods and Appearances. 
Dr, 8. P. BepDson. 
In so short a time as ten minutes it would be impossible to discuss all the evidence 
bearing on the nature of filterable viruses, so that two points only have been selected 
for consideration :— 
1. The fact that, though the size of virus particles varies from one virus to another, 
each species maintains a constant order of size of particle irrespective of the environ- 
ment in which it multiplies. 
2. That each species maintains its antigenic individuality irrespective of its 
environment. 
Experiments with vaccinia, herpes and foot and mouth viruses have shown that — 
the centrifuge enables one to gain a good idea of the size of virus particles, provided 
that the virus suspensions are free from tissue debris and the results so obtained are — 
in keeping with estimates obtained from filtration and ultra-filtration experiments. — 
When the above three viruses, grown in the skin of the guinea-pig’s foot and suspended 
in saline, are centrifuged at 5,000 r.p.m. for 2 hours, the viruses of herpes and vaccinia 
are thrown down to a considerable extent, while the foot and mouth virus is not thrown 
down at all. The virus of psittacosis which is more readily spun out of a suspension 
than either herpes or vaccinia, should be represented by particles of a considerable 
size and almost certainly visible under the microscope. Examination of stained 
preparations shows that this is so. If, then, one is to assume that these filterable — 
viruses are unorganised agents—some sort of self-reproducing disease catalyst—their 
apparent organisation in particles would have to be explained on the assumption 
that they are adsorbed on the particles resulting from the breakdown of cells. And 
the constant size with which each virus species reproduces itself would require the 
further assumption that each virus was selectively adsorbed by tissue particles of a 
constant size. If, however, filterable viruses are looked on as independent living 
agents, this phenomenon of constant size becomes readily understandable. 
The maintenance of antigenic individuality irrespective of the tissue or animal 
species in which a virus is grown is a point of even greater importance. If a human 
strain of herpes is adapted to the guinea-pig and an anti-herpes serum prepared 
therewith, this serum will neutralise specifically not only guinea-pig strains of herpes — 
virus but human and rabbit strains also. The same phenomenon can be demonstrated 
by the reaction of complement fixation, and applies equally to other viruses. Thus, 
an anti-vaccinial serum made with a guinea-pig strain will react specifically with 
vaccinia virus of guinea-pig, rabbit and human origin. Other examples might be 
cited. If filterable viruses are unorganised non-living things, then their multiplication 
in living tissues must result from the affected cells producing more of the agent which 
caused the initialchange. But an agent of this sort would assuredly bear the antigen 
