TJIK ASCUSI'OKKS. 



»3» 



Harr/i. Pcuifoi'ianini I. /lati/n^i. 



S]K>niliiticiri 

 (Ki-iiri-fU al 



A(t«r previoiu Cultivation nt 36 to aj' C. for : 

 34 Hours. 48 Houn. 



29° C. . . . 

 28° to 27.5° C. 

 2.;.5 to 23" C. 

 15 C. . . . 



At the end of 27 hours. 

 It «i 24 ♦• 



II fi 20 ft 



50 .. 



No Sporulution 



At the eml of 36 hours 



•• .. 30 •• 



»i It 54 ii 



The sample previously treatt-d fui- I'oity-eiglit hours gave 

 no sporulation at a tempemture (29'^ C.) at which the other 

 produced spori'S in aVMindance. Apparently this unfavourable 

 etfect is attril)utal)le to the increasivl alcoliol content produced 

 by the longer period of fermentiition. The relation in question 

 has also been observed by other workers, e.7. by H. Mieller- 

 TuuitGAU (III.), A. Adekhold (I.), lire. The (artificially effected) 

 temporary or permanent loss of sporogenic capacity of yeasts 

 will 1)0 dealt with in the chapter on variation. 



The best means of obtaining the moist medium and copious 

 access of air essential to spoiulation, is afforded bv the gypsum 

 block proposed by Enc;el(I.) and suit:il)ly improved by ll.insen. 

 This block is a truncated cone, about 3 to 4 cm. in height, 

 which is prepared, by means of an ungreased mould of sheets 

 iron, from a mixture of S parts, by volume, of powdered, 

 calcined gypsum and 3 parts of water. After the block has 

 become perfectly dry through long exposure to the air, it is 

 placed in a covere<l gla.ss basin enveloped in a double laver of 

 iilterpaper, and sterili.sed in the drying oven for an hour at 

 115° 0. When cold, the yea.st under examination is .sown over 

 the uppei- surface of the block, by means of a platinum loop, 

 previously sterilised by heating to redness. The glass basin is 

 then charged with sufKcient .sterili.sed water to quickly moi.sten 

 the block completely, from l)elow ujiward.s, and in addition 

 leave a layer of watei- about 1 cm. ileep in the bottom. The 

 cover glass should not lit (piite tight, but is prefeniblv supported 

 on an uneven bearing, so as not to exclude the admi.ssion of air. 

 The arrangement of the whole is shown in Fig. 140, about one- 

 half or one-third the real size. The l)lock. in its Iwisin of wat^er, 

 is then placed in a thermostiit, maint;iine<l nt the desired 

 tompei-ature for the experiment. 



Tlie nature of the material composing the moi.--t medium al.*^ 

 iulluences the time limit of sporulation. Since the nece.ssjirv 

 deeming of the gypsum block, by brushing with water after 

 each experiment^ gradually destroys the block itself, H. WicH- 

 MAXX (111.) proposed to replace gypsum by solid cubes of fire- 



