1884.] 



MICKOSCOPICAL JOUKNAL. 



183 



prepared. These are entitled ' Some 

 New Microscopical Devices,' by Dr. 

 R, H. Ward ; ' Description of the 

 Schroder Camera Lucida,' by R. 

 Hitchcock ; ' Demonstration of Per- 

 forations in the Cellulose Walls of 

 Plant-cells,' by Dr. Louis Elsbery. 

 In addition to these a paper was an- 

 nounced by Prof. W. A. Rogers 

 'On the Reproduction of Short 

 Standards of Length,' which was not 

 read. Mr. W. H. Walmesley showed 

 a method of using the electric light 

 in microscopical work. He had a 

 fine Beck's microscope fitted with in- 

 candescent lamps of small size above 

 and below the stage, in which the 

 strength of the light could be per- 

 fectly regulated. 



Celloidine jis an Einbeddiug Mit88. * 



BY PROF. WILLIAM LIBBEY, JR. 



Celloidine is a pure form of pyroxi- 

 line manufactured by a patented pro- 

 cess in Germany, and used largely in 

 photography in place of collodion, 

 and also for embedding purposes 

 in histology. It is prepared by dis- 

 solving I ounce of celloidine in ether, 

 noting the quantity of ether used, and 

 when dissolved an equal quantity of 

 absolute alcohol is added. Two so- 

 lutions are needed, one very thin and 

 the other thick. 



The specimens, after being prop- 

 erly handled, ai'e then soaked in ab- 

 solute alcohol for an hour or two, 

 then for the same period in strong 

 ether, then for six hours in the thin 

 solution and for the same time in the 

 thick solution. 



A good cork must also be soaked 

 in some absolute alcohol, and when 

 ready to embed, this cork is taken and 

 a small quantity of the thick solution 

 placed on one end of it and allowed 

 to dry until it is well stiftened. Then 

 the specimen, with as much of the 

 thick solution as will adhere to it, is 

 placed on this and allowed to dry 

 partially, when another coating is 



•Abstract. Read before Section G, A. A. A. S. 



placed over the specimen from the 

 same solution, and this proceeding 

 ought to be repeated until the speci- 

 men has a sufficient quantity around 

 it to hold it firmly ; then it is allowed 

 to dry and when stiff' is placed in So 

 per cent, alcohol for 1 2 hours at least 

 before cutting. 



The sections are best cut in alcohol 

 and preserved in it until wanted. 

 They can be stained as they are in 

 the mass as it does not stain readily, 

 and then mounted, but they must be 

 cleared up in oil of cedar or origanum, 

 as the oil of cloves usually used dis- 

 solves the mass. 



Where it it important to keep parts 

 of the section in their relative posi- 

 tions the above method of proceedure 

 is best, but where it is of no impor- 

 tance the mass can be removed per- 

 fectly by soaking first in absolute 

 alcohol, then in ether for a few mo- 

 ments, and then putting them in al- 

 cohol again or in a mixture of equal 

 parts of alcohol, glycerin, and water 

 wdiere they will keep indefinitely. 



Methods of Cultivjitiiig Micro- 

 Organisms. * 



BY GEORGE M. STERNBERG, M. D., 

 F. R. M. S., MAJOR AND SUR- 

 GEON, U. S. ARMY. 



That branch of biological research 

 which relates to the lowest and small- 

 est of living organisms, tlie bacteria, 

 or schizomycetes, is second in im- 

 portance to none other, either from a 

 purely scientific or from a practical 

 point of view ; for these lowly plants, 

 in their morphology, growth, and re- 

 production, present to us the simplest 

 possible conditions for the study of 

 fundamental biological problems, and 

 they offer peculiar advantages for the 

 prosecution of experimental research- 

 es bearing upon these problems, by 

 reason of their rapid multiplication 

 and the facility with which species 

 may be isolated and ' pure cultures ' 



•Abstract. Read before Section G, A. A. A. S, 



