374 Journal of Applied Microscopy. 



A New Microscope Objective for Zoological and Dr. H. Harting calls attention to a 

 Other Biological Investigations under Water. i ■ ^- r i i 



Zeits. f. W^ss. Zool. u. f. Mikr. Tech., 12: microscope objective manufactured by 



pp. 1-2, 1S9S. Carl Zeiss, which is suited to the obser- 



tion of living organisms under water, in cases where a wide field and depth of 

 view are desired more than a high degree of magnification. 



It is called the " Planktonsucher." It has a focus of 33 mm., a working dis- 

 tance of 36 mm., and a numerical aperture of 0.11. 



For a tube-length of 16(1 mm. and using the Huyghenian eye-pieces one to five, 

 by Zeiss, the following values may be obtained for magnification and visual field : 



Huyghenian eye-piece. 

 1 



2 



2* 

 3 

 4 

 5 



Eye-piece 2* differs from eye-piece 2 only by its larger visual field. With eye-piece 

 5 the plankton lens gives perfectly clear images so that a magnification of eighty 

 may be conveniently used. Even with the wide field of eye-piece 2 the image is 

 perfectly clear and free from astigmatism. 



For their use in narrow water cells the lenses are fastened in the end of cylin- 

 drical nickeled tubes, so that the water cannot penetrate. 



For holding small organisms in the bottom of the cell, three small strips of 

 glass may be fastened to the bottom, from (1.5 to 1 mm. high, and a strong cover- 

 glass, with diameter a little less than that of the cell, placed on them, so that the 

 object may be kept in a thin layer of uniform depth. E. M. Brace. 



Cleghorn, Allen. Sympathetic Ganglia and ^t was found that an extract of the 

 Blood Pressure. Jour. Boston Soc. Med. sympathetic ganglia of the cat or dog 

 ^■' • ~ ' " ' 99- produced a fall in blood-pressure when 



injected into the jugular or femoral vein. This property of lowering the 

 blood-pressure belongs to the superior and inferior cervical, stellate, and the 

 large ganglia of the solar plexus. Control experiments with spinal ganglia, 

 spinal cord, brain matter, nerve and abdominal tissue produced no results. The 

 sympathetic extract was prepared by macerating the ganglia in glycerine for 

 twenty-four hours, then enough saline solution (0.8 per cent.) was added to 

 slightly thin the extract, and the whole filtered under pressure. 



E. M. Brace. 



Melissenos, C. Ueber Erythroblasten des As is well known at the present time, 

 grossen Netzes. Anat. Anz. 15: No. 22, , 1 i 1 , r 1 1 • 



pp AT,o-42^. ^^" blood corpuscles are found durmg 



embryonic life in the liver, the spleen, 

 and red bone marrow. In later life the marrow alone gives origin to large 

 nucleated red cells, that by the loss of their nuclei become ordinary red corpus- 

 cles. This investigation was conducted on embryo, and newly born cats at a 

 time when the usual blood-forming organs showed activity, the greater omentum 

 being the region particularly investigated. 



