508 SUMMARY OF CURRENT RESEARCHES RELATING TO 



to an ordinary lens-holder, or empty Microscope barrel. The object to 

 be drawn is placed below, without a lens, or with a reducing lens, 

 or in some cases with a lens which slightly enlarges the object. The 

 drawing board is then lowered or raised until the drawing to be made 

 will have the necessary size. It will be observed, therefore, that the 

 whole arrangement is a three-fold one. There is a support for the 

 object, a support for the camera, and a support for the drawing 

 board, and these must be adjustable within the limits of the artist's 

 reach. It will be seen, however, that if two of these are adjustable, 

 the whole system is, for all practical purposes, the same as if all three 

 were adjustable. We now come to the most important matter in con- 

 nection with the use of this apparatus — namely, the: illumination of the 

 object and the illumination of the drawing board. It is possible that 

 it is in this respect that the apparatus hitherto put on the market fails 

 to meet the requirements of the case. It is very desirable to fully 

 control the illumination. Sometimes the object has to be strongly illu- 

 minated, and the drawing board weakly illuminated ; sometimes the 

 reverse is the case, the object has to be weakly illuminated, while the 

 drawing board has to be very strongly illuminated, and the variation in 

 illumination should be as great as possible — from strong sunlight to 

 absolute darkness, if possible. This is the main point in the successful 

 use of the camera lucida for this class of work. This object is attained 

 in the present piece of apparatus by placing the whole at a sunny window 

 and modifying the light by a series of seven roller blinds. One of 

 these, and one of the most important, is the blind attached to the 

 window itself. This does not differ from those elsewhere described in 

 this report. The other blinds for this piece of apparatus have the 

 peculiarity of working in the horizontal direction, the rollers being 

 placed vertically side by side, and enclosed in a light-tight box at the 

 side of the window. The box on the right carries three of these rollers, 

 and that on the left carries a corresponding set of three. These blinds 

 are of varying nature. One of each set is white, another is nearly trans- 

 lucent, and a third is somewhat opaque. By placing these blinds one 

 over the other — that is, by adjusting them properly in the horizontal 

 direction — the light may be varied in any degree required. No way 

 has yet been found by which the light both upon the object and upon 

 the drawing board can be fully controlled by foot-power, as in the case 

 of the Microscope window previously described ; but it is believed that 

 if sufficient thought were given to the subject, such a device might be 

 evolved. In the meantime, the present arrangement works fairly satis- 

 factorily, and avoids the use of complicated apparatus between the eye 

 and what it is looking at, in the same way as does the apparatus 

 previously described in connection with the Microscope window. 



Quekett Microscopical Club. — The 432nd ordinary meeting of the 

 Olub was held on June 15, the President, Dr. E. J. Spitta, F.R.M.S., 

 etc., in the chair. Mr. A. E. Hilton read a paper " On the Study of the 

 Mycetozoa." The names by which this group has been known were 

 mentioned, and their distribution, habitat, and life-cycle, together with 

 the method of classification, were described. The literature dealing 



