6i) 



and the solutions were then ready for the preparation of the 

 hanging drops. 



The drop cultures were made after much the same method 

 as that described by Clark-^^. Tan Tieghera cells were used, 

 small glass cylinders with ground ends, 9 mm. high and 12 mm. 

 in diameter, which '^ere cemented to common microscope slides 

 by means of beeswax. Two cells were affixed to each slide. 

 The culture solutions in the glass dishes, into which spores 

 had been inoculated, were thoroughly mixed with a glass rod, 

 by means of which a drop of the liquid '.vas then placed upon 

 a flamed cover glass. 



A small drop of the culture solution from the cor- 

 responding flask without spores was placed in the bottom of 

 the Tan Tieghem cell and the cover bearing the drop culture 

 was inverted over it. Duplicate drop cultures were made 

 from each concentration of the solutions, both cultures be- 

 ing placed on the same slide. As has been shown by Clark, 

 the presence at the bottom of the culture cell of a small 

 amount of the same solution as that from which the hanging 

 drop is composed, prevents evaporation from the drop and 

 hence obviates markeJ alteration in its concentration, even 

 if the cultures remain in the thermostat for a considerable 

 time. Without this precaution the solution contained in the 



12. Clark, J. F., Cn the toxic effect of deleterious agents 

 on the germination and developement of certain filamentous 

 Fungi. Eot. Gaz, 28:289-327 and 378-404. 1899. 



