Journal of Applied Microscopy. 653 



The experiments gave no evidence in support of the theory that the circular, 

 quiescent form of amoeba represents full contraction. The writers believe that 

 the distinction of entosarc and ectosarc is purely arbitrary, depending upon the 

 distribution of granules in the protoplasm, and that it is not a fundamental 

 difference. 



Large amoebae were used for the experiments and the motions were studied by 

 means of images thrown upon a screen by a large electric projection lantern. Light 

 filters of colored celloidin, used by Bierstadt in photographing colors, interposed 

 between the amoeba and the arc lamp produced the quick changes of color required. 

 Although such light is not purisly monochromatic, the same results were obtained 

 as when monochromatic lights were used. Experiments of this sort are well 

 suited for class demonstration. e. m. b. 



NOTES ON RECENT MINERALOGICAL 

 LITERATURE. 



Alfred J. Moses and Lea McI. Luquer. 



Books and reprints for review should be sent to Alfred J. Moses, Columbia University, 



New York, N. Y. 



A. Arzruni and K.Thaddieff. New Minerals from The late Prof. Arzruni left unfinished 

 Chili. Zeit. f. Kryst, 31 : 229, 1899 ^^^ description of several new Chilian 



minerals. This work has been completed by A. Dannenberg. 



Arzrunite. — A brilliant bluish-green mineral occurring as minute crystals 

 and druses in the hollows of a porous quartzose rock from Mina Buena Esper- 

 anza, ChallocoUo, Tarapaca, Chili. 



The crystals are by measurement geometrically hexagonal prism, pyramid 

 and base, but being strongly pleochroic at right angles to the vertical axis and 

 biaxial in convergent light, they are described as orthorhombic with a : b : c= 

 0.5773:1 : 0.4163. 



After deduction of numerous impurities the formula given is PbS04. PbO-f- 

 3 (Cu CI2 H2 O) + Cu (0H)2. 



Stelznerite. — Beautiful green transparent crystals of brilliant luster occur- 

 ring upon a somewhat similar spongy mass of a brighter green color. 



The crystals are orthorhombic, showing prism, pinacoids 010 and 001, pyra- 

 mid and dome Oil. The axial plane is parallel 001, the axes emerging almost 

 perpendicular to the prism faces. Pleochroism, blue green to yellow green, a : b : c 

 =0.50368 : 1 : 0.70585. 



Analyses yield formula CUS04. 2 Cu (OH) 2- Mineral resembles brochantite. 



Locality, Remolinos, Vallinar, Chili. 



Rafaelite. — At Mina San Rafael, Sierra Gorda, Chili, there occur violet 

 red needles 0.5 to 1 mm. long and 0.2 to 0.5 mm. broad, forming a drusy coat- 

 ing upon galenite, quartz and celestite. Schwarzembergite is also found. 



The crystals are monoclinic and show several domes terminating a vertical 



