The work of research in the sister sciences and by other methods has, during the last decade, received a corresponding impetus, while it has undoubtedly tended towards elaboration and specialisation in all departments. In consequence, the progress of microscopical science has become more dependent upon the specialist for gaining accurate knowledge and for certain important details seen to be branching out in many directions. There never was a time when the instrument was so constantly and generally resorted to and with so much confidence and advantage, as the present. It has shown itself equal to the task imposed--that of teaching the eye to see things that are new, and also, what is perhaps of more importance, to perceive things which had been entirely overlooked. The older defects, perhaps, arose from two causes; the want of more careful training of the organ of vision, and the want of sufficient power and precision in the optical part of the Microscope itself. Both of these obstacles have been to a considerable extent removed, and all educational systems are looked upon as incomplete without a knowledge of the Microscope. A step has already been taken in another direction, that of furnishing special forms of instruments, better adapted to the uses to which they will hereafter be put, and purposely designed for chemical and analytical processes, for petrological pursuits, the geometrical measurement of crystals, for special work in connection with manufacturing industries, for the dairyman, and the farmer. For the detection of adulterations--that of butter, for example--a newer form of instrument has been devised, namely, a “Butro-refractometer,” by the help of which any adulteration of this universal article of diet will at once be revealed. The form of instrument upon which the optician has expended a greater amount of skill than perhaps on any other is the Bacteriological Microscope, as may be inferred from the larger space I have devoted to this important adjunct, since by original research, there can be no doubt a still greater future is in store for science in this special department of microscopy. But perfect success in this direction remains very much with the practical optician, and the further improvements made in the optical part of the instrument, since it is admitted that the highest theoretical perfection has not yet been reached.