THK ASCO.SPOUES. 135 



ou I'luiich wiiiL' yeiisi ; K. AuKiinoLD (!.), on German wini* 

 yeasts; A. Nastukokk (I)., on Kiissian wine yeuhts ; antl W< 

 Seikkkt (I.), on Anstiiun wine yeasts ; also by E. Kayseu (III.), 

 on Kreiirh friiit-wine ynusts ; :in«l l.y Cliit. (Jicikniaxd (I.), 

 J. Cm:. XiELSEN (I.), an.l Al.U. KliKCKEK (I.), (jn several species 

 still to be mentioned. The main object of such investifrations 

 is the tleteimination of the niiniiuiini, niaxiinuni, an<l optimum 

 tempeniture of sporulation ; ami several complete series of 

 similar ilatii have been compiled. The relation between the 

 hoi^dit of the thermometer and the time limit of incijtient sp^nu- 

 lation in a ^'iven species may nlrn) be ;;raphicallv e.\pres.se<l bv 

 plotting; the temperatures a.s absci.s.sje and the correspomliiifr time- 

 limit values as ordinates of a rectanjjular sysk-m of co-oitlinates, 

 and connecting,' the points of inter.section l)y a line. Such lines 

 are mostly termed spondatimi cin-ves, in the liteniture of the 

 sul)ject. 



The percentiige mtio of the number of sj>orogenic cells to 

 the totiil cells present differs -rreatly accordinj: to the specie.^, 

 orijjin, kind of previous nutrition, A:e., but in most species fails 

 U) attain even aj>pro.\imately to 100. In many of the cultivated 

 yeasts, e.tj. five out of thii-ty-two species of lH)ttom-fermentJttion 

 l)eer yea.sts e.xamineil by L.vsrni'; (IV.), no success has, so far. 

 attended the attempts made to brin<; about sporulation ; con- 

 sequently fen- the present these cannot be regarded as So'-chartj- 

 iinji-i-ti't!. 



On the basis of his e.vperimental results in connection with 

 sporulation. already alludeil to, Hansen has worke<l out a method 

 of biological analysis for brewery stock yea.st^s ; antl this niethoil 

 has been fuithei- developed, especiallv bv J. C'nu. Holm and 

 S. V. PoiLsKX (Land II.). 



The term "culture yeast'' is applieil to such yea.sts us have 

 been cidtivated for practical use in fermentation technologv, and 

 have then been em|)loyed thei-ein. M»)re than this is not imj»lieil 

 by the expression, nor does it apply in any way to their origin. 

 On the other hand, the yea.sts njet with wild in nature are termetl 

 generally wild yeasts. Many of these are harmle.s.s, though 

 others, as alri'ady mentioned in J; 2.15, are capable of pinxlucing 

 distnrl>ances on gaining acce.ss to the opei-ations of brewing, i^c. 

 and are then spoken of as (technically) pathogenic. E.vaujples of 

 this class are atVorded by SarrJi. I'(i.<f. I. 11. , which imparts a 

 repulsive bitter taste to beer; also Sa^rh. J\ist. HI. 11. and 

 Sw'i'h. elfi/is. II. II.. which pnxluce haze. As a further deduc- 

 tion from the observations of H.insen that the wild veasts in 

 geneial foiiu a.scospores more cpiickly and abundantly than the 

 lH)ttom-fermentation (culture) beer yea.sts. Hohu an<l Poul!^?n 

 have shown that the latter «in be clji.ssified into three gi»ups 

 according to their beh.iviour in this resjHvt. The member", of 

 the first grouj> reinain sp»>reless. Ixith after seventy-two hours at 



