“The typical bacteriological microscope should be well equipped with objectives of sufficiently high magnifying power, and with a special form of illuminating apparatus; while the mechanical arrangements for focussing should act with the greatest smoothness and precision; the stage, also, should be wide enough to admit of the examination of plate cultivations.” We will consider these several points and recommendations _seriatim_, commencing with the stand. Messrs. Watson & Sons’ Van Heurck model stand so well answers the several conditions laid down by an experienced teacher of bacteriology, that I have no hesitation in presenting it to my readers as a typical instrument, one in every way worthy of the high praise it has already received from those who have worked with it, and whose judgment may be relied upon in every way. The microscope is fully described among Messrs. Watson’s instruments, page 108. _The Stand._--A good firm stand is undoubtedly of the first importance for all high-class work. The steadiness of the instrument and its entire freedom from vibration depends largely upon the form of the stand. I am glad to find Dr. Crookshank in accord with me as to the Ross-Jackson model, one which, in my opinion, has not been entirely superseded by models of a more recent date. Indeed, the latest improvement effected in the Ross-Jackson form, in which attention has been given to the spreading-out of the feet, has converted it into as solid and firm a stand as Powell’s; it is equally free from vibration when placed in the horizontal position. There are, however, four different forms of stands--the tripod; the plate with double columns; the single column ending in a plate or a bent claw; and the horse shoe. The tripod stand, with cork feet, is by far the steadiest form of model. The single upright pillar support should unquestionably be condemned, as it admits of considerable vibration, and is most inconvenient for laboratory work. The heavy horse-shoe form is compact and firm, and the weight of it can hardly be considered an objection.