THK A.SCUSl'OKKS. 129 



tioii of the cells is «ti<ni;j[ly .stiiiiuliite<l, iicceleniUjil, and in- 

 tTeased. W'Iumi tfiiuentiitioii is at an oml the contents of the 

 ferment iii}j; vessel are cooled ami <lni\vn off into lar;;e, Ihit 

 claril vin",' j»ans, where the yeast crop settles down, and, after 

 the removal of the supeinatalit li(|iud foi- distiUation, is wahhe^l 

 with water and finally forced int<j tilt*'r presses, where it is 

 l)rou;,'ht into s;ileal)le c(jndition. Occ^isionally the dej)osition of 

 the ye;u>>t crop in the chirifyin;; pans, and therefore its hepamtion 

 from the licjuid, is obstructed l>y a so-called llocculenee, which 

 is characterised hy the continued re-ascension of flocculent 

 jij^fjref^ations of cells from tl»e dej»osit. The phenomenon has 

 been descrilied by Stkmm.kin and JuEUUES in "' Alcohol" (i8y2, 

 p. 2l8), and also by < >. I )i i;sr (1.). 



§ 247.- The Ascospores. 



The first observation of the ascospores in yeast cells was 

 made by Tn. Schwann (II.). He pointed out that the.se fungi 

 reproiluce in two ways : one being by the process known as 

 budding, and the other liy the formation, within the parent-cell, 

 of daught»'r-cells, whicii are libcrateil when the niemltrane of the 

 parent-cell opens. After this phenomenon had been described 

 more closely by J. ije Skvnks (I.) in 1S6S, it was al.so observed 

 a year later by ^I. Reess (111.) in i-ultures of beer yeast on Iwiled 

 .sections of carrots, «\:c. He found the pi'ocess of development 

 coincide with that of certjiin low Atfrumyceifs, and therefore 

 das.seil these forms as ascospores, i-alling the mother-cells a.sci, and 

 for this rea.son relegating the i>ui-r/iaroiiii/nttn (^\i\ 1 8 70) to the 

 position of the lowest family among the Asroini/reteti. 



The earliest accur.ite investigations into the conditions under 

 which this sporulation occiu's were carried on by E. Chr. 

 Hansen (XII.), and, a[)art from the general biological results, 

 led to the injportnnt fiu't that we have here a reliable meiins, 

 hitherto lacking, of .separating the genus tSaccliaromyccs into its 

 .sj)ecies. 



The conditions influencing the production of ascos|H>res in 

 the i^airharomiji-etfs tu-e given below: (1) To obtain energetic 

 sporulation, it is neces.s;iry that the sjimple should consist of 

 young and well-nourished cells. (2) The supply of air must be 

 abundant. (3) Tin- metlium nuist be moist. (4) The tempeni- 

 ture of the envii-onment must be maintained within certain 

 limits. (5) Within these limits the time required for the 

 occurrence of sporulation is a function of the t4.«mpeniture. 

 (6) Between the two extreme limits at which sp«irulation is still 

 possible is an optimum temperature corresponding to a time 

 minimum. The maximum tempeniture for sporulation is some- 

 VOL. II t 



