1919) 



WEBB — SPORE GERMINATION AND H ION CONCENTRATION 



209 



sterile, glass rod drawn to a small point. The cover glass bear- 

 ing the culture was then inverted on the cell and gently pressed 

 until completely closed with the exception of the minute opening 

 previously described. All cultures were made up at room tem- 

 perature, and, when a set of cultures was completed, all were 

 placed in an incubator and kept at a constant temperature. 

 Cultures of each organism were incubated at 22° C, 27° C, 

 and 31° C, respectively, with the exception of Lenzites saepiaria. 

 Care of cells, etc. — The glass rings and slide composing the 

 cells were never used a second time without being taken apart 

 and thoroughly cleaned by boiling in alkali, soaking in cleansing 

 mixture, and repeatedly rinsed in distilled water. They were 

 then sterilized in an oven at 150° C. for 1 hour and protected 

 from dust until needed. The cover glasses were treated simi- 

 larly except that they were boiled longer in order to remove all 

 traces of vaseline, and finally dipped in alcohol and wiped dry. 

 All slides, rods, etc., were placed in water after having been used, 

 and given the same general treatment before setting up another 



series. 



Examination of cultures and data. — Cultures were made up, 

 as a rule, in the afternoon and examined at different intervals, 

 depending on the length of time required for the spores of a par- 

 ticular organism to germinate, as determined by a preliminary 

 experiment. Spore counts were made from five fields of the 

 hanging drop, and the average percentage of germination re- 

 corded. Where possible three different readings were made with 

 each set of cultures, but often the mycelial growth was so luxur- 

 iant that only two were possible. All of the experiments were 

 run in duplicate, and the germination data reported in this 

 paper represent the percentage averages of the two cultures. 

 Although slight fluctuations occurred throughout the work, the 

 result from any cell agreed very closely with that of the dupli- 

 cate. 



Curves. — The curves are developed from the percentage 

 averages, as indicated above, each curve representing the final 

 readine: of the termination Quantities of a certain organism at a 



temperature 



germination 



plotted as ordinates and the hydrogen ion concentration of 



