26 Avoiding the Use of the 



fungi, it is stated that the male organs never produce anthero- 

 zoids, and that the cystidia are always deprived of sterigmata or 

 spicules. 



To repeat and follow out these observations it is necessary to 

 take the specimens for examination exactly at the proper period of 

 growth, and to exercise the greatest care in securing a uniform 

 moisture between the glasses. The life of the fungus is so short, 

 and all the characters are so evanescent, that the points to be 

 observed may be present one moment and all gone the next. 



All the drawings have been made with a camera-lucida, and 

 from diflferent specimens, so where the dimensions of the parts 

 slightly disagree, it is only such a disagreement (within defined 

 Hmits) as is commonly found in Nature. — Gardeners Chronicle, 

 October 16 and 23. 



III. — Avoiding the Use of the Heliostcd in Micro-photography. 



By G. M. Giles, M.M.M.S. 



Plate CXXVII. 



Some time ago I commenced to make some experiments in micro- 

 photography. I did not wish to set aside a room to act as a camera, 

 as in the method of Colonel Woodward, and did not like the form 

 of instrument mentioned in the catalogues of the instrument makers, 

 as in the first place it is very top-heavy, and in the second the 

 disk produced, I found on inquiry, was no larger than a " five-franc 

 piece." Above all things I wished to avoid the necessity of using 

 a heliostat. 



I was therefore constrained to contrive an apparatus to meet 

 these requirements, which I have no doubt are those of a great 

 many histologists. The image produced by an ordinary condenser 

 of short focus is so small, that unless a heliostat be used, it is almost 

 impossible to replace the focussing screen by the sensitized plate 

 before, on account of the rotation of the earth, the image has passed 

 across the field of the instrument and disappeared. Now the obvious 



EXPLANATION OF PLATE CXXVII. 



Figs. 1 and 2, a. — Stand of camera. 



b. — Mirror. 



c. — Long-focussed condenser. 



d. — Microscope and its slider. 



e. — Grooved wheel at back. 



/. — Strings of horizontal movement. 



g. — Strings of vertical movement. 

 Fig. 3. — Section mode of connection of microscope with camera. 

 4. — Sectional view of " tramway." 



