46 
puzzles him, because Mr. Barrett mentions the “ blue sky and bright 
sunshine of Pembroke ; ” so also does the pure air and bright sunshine 
of parts of Scotland, for Mr. Birchall says, that in some of these melanic- 
producing districts “ the air is purity, and the sunshine brightness?” 
he is puzzled at the sunlessness of Ireland and the Isle of Man, and the 
want of influence of the Gulf Stream on the coast of France. In fact, 
many things puzzle Mr. Robson, but these he nobly leaves to the meteor¬ 
ologists of Ireland. “ Sufficient unto the day is the evil thereof,” and 
Mr. Robson showed his evident pleasure when he reached the end of 
his paper, at having pulled through a task which he set himself 
thoughtlessly, stated his intention of doing publicly, and which he 
carried through nobly for the sake of his prestige. 
But if Mr. Robson’s paper be not a personal attack, I would ask him 
for a few facts, which any article meant to be a contribution to science 
would have contained, and which it was Mr. Robson’s duty to have 
found out by experiment. (1) What percentage of the sun’s rays are ab¬ 
sorbed or intercepted on the West coast of Ireland, East coast of Ireland, 
Isle of Man, Scotland (West and East), Shetland, Yorkshire, Derbyshire, 
and other areas given to producing melanism ? (2) What percentage 
of these rays are distinctly chemical in their tendency ? (3) What ex¬ 
periments has Mr. Robson conducted to show, that the areas where 
melanism prevails, do have a large percentage of the sun’s rays inter¬ 
cepted ? and will he give us one experiment that he has conducted to a 
successful issue, which bears out his views ? If he has done none, where 
is the science in his paper ? Is it not rather an essay, based on imagi¬ 
nation, rather than a theory, based on facts ? All these assumptions that 
things are so, are not science. The New Forest, where black obscurata 
occur; the coast of Kincardine, where black lucernea are found; the 
Welsh parks, where dark crepuscularia occur; Delamere Forest, where 
black betularia is common ; Lewes, where black Agrotis cinerea occur ; 
Deal, where black Agrotis corticea occur, have deficient sunlight ( teste 
Mr. Robson). Where are the experiments that warrant such assump¬ 
tions ? No, Mr. Robson ! it will not do ! “ Natural selection ” is not 
dead yet, and your paper has not proved that we have anyone to replace 
Darwin. 
In the discussion that ensued, Mr. Lewcock drew attention to the 
fact that species frequently showed a distinct and constant tendency to 
vary in a particular direction, apart from the more polymorphic ten¬ 
dencies to general variation frequently observed. Mr. Bacot said that 
he could hardly understand the application of the suggestion that dark 
colours on the wings of lepidoptera were more advantageous to them 
than lighter colours, by absorbing more heat, as it was the bodies of 
insects which were required to benefit by such an advantage, and not 
the wings. Mr. Tutt said that some observations he had made under 
the microscope seemed to bear out Mr. Bacot’s view, as the wing 
appeared to cease to be a vital organ very early indeed in the imaginal 
life, and that the absorption of heat by the wings would, under those 
conditions, scarcely affect the vital functions of the imago. 
On the motion of Drs. Buckell and Sequeira, a vote of thanks was 
accorded to Mr. Tutt for his paper. 
Tuesday, 16th May, 1893.—Exhibits:—Mr. Smith, Eurymene dolo- 
brana and Ephyra trilinearia, from Epping Forest; one of the latter 
