666 
SUMMARY OF CURRENT RESEARCHES RELATING TO 
objective, his “ specific function of the aperture,” and takes it as the 
starting-point of a theory of microscopic vision. To the latter the 
author raises objections, although he admits that the experimental data 
are beyond doubt, His idea is that the theorem is an immediate conse- 
quence of the diffraction on the edges of the diaphragm which limits the 
aperture of the objective, and that consequently the specific function of 
Abbe is nothing else but the diffraction produced by the edges of the 
aperture. 
C6) Miscellaneous. 
Dr. Dallingers Address to the Quekett Club.* — The Rev. Dr. 
Dallinger said : — “ In addressing you to-night, as President of our 
Club, I shall keep before me the fact that, whilst we seek as a Club to 
prosecute all our mutual and individual inquiries in a completely 
scientific spirit, many amateurs are included in and welcomed by the 
Club, and that we aim at promoting and aiding early efforts with our 
favourite instrument, quite as much as criticizing the last results of 
experienced research, or the latest endeavour to render more perfect the 
instruments with which we work. 
Keeping these facts before me, I am strongly impressed with the 
conviction that no subject can have a more general area of interest 
among microscopists than the work being done regarding the nature of 
the animal and vegetable cell. To what extent a full and complete 
knowledge of animal and vegetable cellular life and history, leading to 
a full grasp of the comparative physiology and morphology of cells, may 
ultimately contribute to a completing of our knowledge of life and 
function in animals and man, it may not be possible to say ; certain it is 
that what we already know has profoundly affected our insight into 
animal structure ; but our progressive and further knowledge of the 
structure of the tissues that form the body, and of their physiological 
and even pathological action, must be concurrent with our advancement 
in this subject. 
Upon the progressive excellence, therefore, of the Microscope as an 
instrument of precision on the one hand, and upon the increasing 
delicacy and skill with which we are enabled to prepare tissues for 
examination and progressive research with that instrument on the other 
hand, must depend our advancement. 
Whatever leads to more perfect optical construction is an essentially 
good thing ; and what is sometimes cavalierly treated as “ amateur 
microscopy ” has contributed largely to optical advancement. 
It is alter all “ the battle of the lenses ” that has led up to, and called 
into existence, the splendid lenses of to-day. But this was, for all 
practical purposes, a battle fought by amateurs and opticians. Our 
schools of biology in England, the Continent, and America took little, if 
any, part in it. Yet without question it is the students in our great 
biological schools who are deriving the largest benefits from the splendid 
improvements in quality, price, and modes of using recent Microscope 
objectives. 
By apochromatism the study of ultimate cell-structure and cell change, 
* Joum. Quek. Micr. Club, iv. (1891) pp. 304-14. 
