ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 



99 



(1) of a comparison light-source 0, whose intensity can be weakened 

 by a double sector S ; (2) of a Lumrner-Brodhun comparison cube 



P. adjustable both for equality as well as for equality and contrast ; 

 (3) of a tube h 3 (fig. 20) for the reception of the light to be measured 



h 2 



