THIELAVIOPSIS PARADOX A. 543 



as far as possible with the same number of spores by suspending 

 the latter in water and adding equal amounts to each. One 

 of these was left on the laboratory table exposed to diffuse 

 dayHght, while the other was kept in complete dai-kness. 

 After seven days the contents of both were filtered tlirough 

 tared lilter papers, washed well with distilled water, and dried 

 until the weight was constant. The dry weighLof the culture 

 grown in the dark was • 270 grams ; that of the culture grown 

 in diffuse light was 0'143 grams. 



The experiment was repeated, and the product dried and 

 weighed after four days ; the dry weight of the culture in the 

 dark was 0-080 grams, while that of the culture in the light 

 was • 056 grams. There was no difference in the appearance 

 of the two cultures ; both in the light and in the dark they were 

 black with macroconidia. It would appear, therefore, that 

 Thielaviopsis grows more luxuriantly in darkness than in 

 the hght, and that the absence of light does not prevent the 

 production of conidia. 



The Longevity of the Spores. 



The following experiment was instituted to determine how 

 long the spores retained their germinative capacity under 

 different conditions. The nutrient solution was poui-ed away 

 from a large flask culture, about ten daj'S old, which contained 

 an abundance of macroconidia. The mass of mycehum and 

 spores was then shaken well with steriHzed water, and the 

 liquid with the suspended spores was poured through a filter. 

 The process was repeated until a dozen filter papers uniformly 

 covered with black spores had been obtained. These were 

 then allowed to dry at the room temperature. Each filter 

 paper was cut into four numbered pieces to secure uniformity 

 as far as possible, and these were arranged in four lots as 

 follows : — 



A. — In a desiccator over calcium chloride in semi-darkness. 

 B. — In a closed and sealed glass vessel in semi-darkness. 

 C. — In a desiccator over calcium chloride exposed to full 



sunhght for four to six hours per day. 

 D. — In a closed and sealed glass vessel exposed with C. 



