700 GENERAL TECHNIQUES FOR CLASSES OF PLANTS 



flasks. The new Holden flask (Holden, Ann. BoL, xliv. 1935, 

 p. 401) has several advantages ; it largely obviates contamination 

 and drying out of the medium and permits easy access to the 

 colonies. 



See ScHW^izER, Planta, vii, 1929, p. 118, for a method of 

 culturing coprophilous Ascomycetes cleanly; Bodine, Science, 

 Ixxiv, 1931, p. 341 (double plate method for Tilletia ; Carleton, 

 J. Appl. Micr. Lab. Meth., vi, 1903, p. 2109 ; Conn, J. Bad., iii, 

 1918, p. 115). 



1392. Vernon's Moist Chamber {Ann. Bot., xlv, 1931, p. 733) 

 is a useful device for observing sporangium formation, etc. Put 

 a drop of agar culture medium on a slide. When it is cool to about 

 the point of gelation, put a cover-glass on it and flatten out the 

 drop of medium considerably. When the medium is hard, remove 

 the cover-glass and cut the flattened drop through the middle, 

 pushing one of the halves a little to one side, leaving a channel. 

 Inoculate one of the halves along this side and replace the cover- 

 glass. The aerial hyphae and conidiophores growing into the 

 channel are at right angles to the line of division. 



See also Bachmann, Cifferi (§ 1394) and Rivalier and Seydel 

 {Ann. Parasitol. Humaine et comp., x, 1932, p. 444) for methods 

 of culture on slides. 



The preparation of culture media is largely outside the scope of 

 the present work. See Rawlins, Chapter III ; Gwynne-Vaughan 

 and Barnes, The Fungi ; Harshberger, Mycology and Plant 

 Pathology, 1917, p. 581 ; Levine and Schoelein, A Compilation 

 of Culture Media for the Cultivation of Micro-organisms, Wifliams 

 and Wilkins Co., Baltimore, Md., 1930. 



1392 bis. Isolation of Single Spores or Bacteria. Stoughton {A System 

 of Bacteriology in Relation to Medicine, H.M. Stationery Office, ix, 1931, 

 p. 100) has summarised the more important methods. See also Davis 

 {Proc. Iowa Acad. Sci., xxxvii, 1930, p. 151). 



1. Growth of a single selected cell in a smear on a suitable 

 medium or in a dilution plate under direct microscopic observa- 

 tion, and its transplantation. 



BuRRi, Das Tuschverfahren, Jena, 1909 ; Ezekiel, Phytopath., xx, 

 1930, p. 583 (streak method) ; Gardner, J. Path. Bact., xxviii, 1925, 

 p. 189 ; HoKT, J. Hyg., Camb., xviii, 1919, p. 361 ; La Rue, Bot. Gaz., 

 Ixx, 1920, p. 319 (dummy nosepiece) ; 0rskov, J. Bact., i, 1922, p. 537 ; 

 Reimann, J. Exp. Med., xli, 1925, p. 585. 



2. Preparation of a hanging-drop containing a single organism 

 which is then picked off by some mechanical device. 



Barber, Philipp. J. Sci., ix, 1914, p. 307 ; Chambers, J. Infect. Dis., 

 xxxi, 1922, p. 334 ; Greene and Gilbert, Science, Ixxv, 1932, p. 388 ; 

 Malone, J. Path. Bact., xxii, 1918, p. 222 ; Peterfi, Handb. biol. 

 Arbeitsmethoden {Aberhalden) Abt. v. Teil ii, 1924, p. 479 ; Schouten, 

 Verh. Akad. Wet. Amst., Sect. Sci., xiii, 1911, p. 840. 



