OBITUARY. 
FRANCIS ORPEN “MORRIS, M.A. 
Born Marcu 25, 1810. DiED FEBRUARY 16, 1893. 
RITISH Naturalists will learn with regret of the death of the 
Rev. F. O. Morris, which took place at his residence, the 
Rectory, Nunburnholme, Yorkshire, on February 16. Of those 
devoting themselves to the spread of an interest in Natural History 
pursuits among the unlearned, Mr. Morris had long been a con- 
spicuous figure; and his success was gained both by the charm of 
his personal enthusiasm and by the numerous, well-illustrated 
popular writings which enabled him to reach a wider circle. His 
best known and most valuable works are his ‘‘ Histories” of British 
Birds, their nests and eggs, and of British Butterflies and Moths, 
the publication of the first commencing in 1851. The new school 
of Biology inaugurated by Darwin and Wallace, unfortunately, never 
found favour with Mr. Morris, and his long series of miscellaneous 
writings antagonistic to this school began with a small volume on 
««The Difficulties of Darwinism,”’ published in 1870. 

CORRESPONDENCE. 
A HypoTHETICAL EXPLANATION OF THE RESULTS OF INOCULATION. 
Mr. Burman sets forth (NATURAL SCIENCE, vol. ii., pp. 100-109) the arguments 
for and against two theories—the ‘‘ Exhaustion Theory” and the ‘‘Antidote Theory.”’ 
Another explanation has been familiar to me for some time and to this he has not 
referred; I greatly regret that I am unable to say where I got it from, but I 
rather fancy some part of it was ‘‘evolved out of the depths” of my own ‘inner 
consciousness.”’ 
It is as follows :— 
The attenuation of the virus by cultivation under conditions unfavourable to 
the microbe’s very rapid multiplication amounts to an artificial selection, the too- 
rapidly-multiplying stocks being exterminated by overcrowding and the poisonous 
effects of their own products. After several cultures, each raised from the survivors 
of the preceding ones, an ‘‘attenuated virus’ is obtained, 7.e., a pure culture of those 
stocks whose rate of multiplication is low. 
The selection may, however, act in some other way—the net result being that the 
final culture consists of those stocks which, however they may behave on gelatine or 
boiled potatoes or in chicken-broth or the blood of living apes or guinea pigs, are 
