119 



Achromatic Objectives, 



With each homogeneous immersion objective ive supply free 

 of charge one MACH'S oil drop-bottle and about 15 grammes of 

 cedar-wood oil (see page 117). 



Glass Trough for Objective PI (Plankton - Searcher), Price: Marks 3.50. 

 Code-word: Pajarita. 



, Sena. 



