1820 Journal of Applied Microscopy 



tate formed by the mixture is redissolved. After staining, the sections are washed 

 quickly in absolute alcohol and differentiated in clove oil. When the proper 

 differentiation is secured, the clove oil is removed with xylol, and the sections 

 mounted in balsam. c. a. k. 



Metzner, R. Untersuchungen an Megastoma This peculiar flagellate occurred as a 

 entericum Grassi aus dem Kaninchendarm. -^ • ^i • ^ ^' r ^ t ^^ 



Zeitschr. f. wiss. Zool. 70: 299-320. Taf. parasite m the intestme of most of the 



15. i9°i- rabbits in the warren of the Physiolog- 



ical Institute at Basel, and the author was able to secure abundant material for 

 his investigations. The parasite usually remains attached to the intestinal villi 

 so closely that clean preparations for microscopical examination are secured with 

 difficulty. In one instance a rabbit was examined in which the intestine for a 

 distance of 25 cm. below the pylorus contained only a clear fluid stained with 

 bile, in which immense numbers of the flagellate were found in a free swimming 

 state. From such material it was possible to secure clean preparations. Fresh 

 preparations were examined in the hanging drop, which should be made as flat 

 as possible. Oil immersion lenses can be used on such preparations, but the 

 animals perish very quickly. On account of the rapidity with which abnormal 

 conditions affect this parasite, it is necessary to take many precautions to preserve 

 it. The body of the host should be kept at the normal temperature and the tran- 

 sition from the host to the fixing fluid should be made as quickly as possible. 

 Cover-glass preparations were made as follows : Clean cover-glasses were rubbed 

 with a linen cloth into which a trace of glycerine had been rubbed and a drop of 

 the fluid contents of the intestine carefully flooded on the moistened surface. The 

 cover-glass is then placed preparation side down upon the surface of the fixing fluid. 

 The fluid used was prepared as follows : A 1.5 per cent, solution of sodium 

 chloride is saturated with osmic acid (5.5 parts osmic to 100 salt solution) and 

 to 7 volumes of this is added 1 of a saturated aqueous solution of bichromate of 

 potash (mixture No. 2). Just before using, 2 to 4 drops of fuming nitric acid are 

 added to 12 cm.^ of this fluid (mixture No. 1). The amount of nitric acid may 

 be increased to 8 to 12 drops. When the preparations are to be fixed the two solu- 

 tions are placed in watch glasses beneath bell jars. The cover-glass prepara- 

 tions are placed for 2 minutes in mixture No. 1. If 8 drops of the nitric acid 

 have been added to the osmic-bichromate solution, the time may be reduced to 

 30 seconds ; if 12 drops, to 20 seconds. They are then placed for 10 to 20 minutes 

 in No. 2, washed in distilled water and passed through alcohol grades. The 

 preparations were stained in acid-fuchsin for a few minutes at 55° to 60°C. or 

 for 1 to 3 hours at 40° in thermostat. After staining, the preparations were differ- 

 entiated in picric alcohol of two grades ; (1) saturated solution of picric acid in 

 absolute alcohol 1 vol., 20 per cent, alcohol 4 vols. ; (2) same ingredients in 

 proportion of 1 to 7. The stronger solution should not act longer than 1)^ to 2 

 minutes, and further differentation should be controlled under the microscope. 

 Preparations were mounted in xylol-dammar and examined with oil immersion 

 objective and artificial light. For protection of the eyes against fatigue and to 

 bring out the finest details of structure, the author employed a globe filled with a 

 solution of chlorophyll (0.5 cm.^ of alcoholic cholorophyll extract to 1500 cm.'' of 

 distilled water) and hung in a circular opening of an asbestos screen, c. a. k. 



