(JKK.MINATION ( )l' SAl'CHAllOMYl'ETES. 



»37 



Till- examination of tlit* top - I'ci mentation beer yeaBts, 

 <listilleiy yeasts, ami pressed yeasts liy this process is a more 

 ilelicate operation, because tliey sporulate much eailiei- an<l 

 more abuiulantly than tin- bottom Icrmcntation yeasLs ; fur in- 

 stance, a species from the Munich lirewinj: Station, examined l)y 

 AVili, pro<hice<l spores in fourteen houis. Ncveitheless, according 

 to JcEKGEXSEN (VIII.), the test is applicabh^ if knv temjienitures 

 (i2° C.) be emph)yed. The wine y»*asts spoiidate still more 

 rapidly, 46 out of 58 examined by Maix beiiij,' fciund to pro- 

 duce spores within twenty-four hours at 25^ C. Similar results 

 were obtained by Aderliold and by Nastukitti". The proposed 

 supercession of spore analysis by the small-drop culture method 

 introducetl by P. l^iNUNKii (X V.), will be referred to later, in a 

 jiaragraph dealing with puie culture apjilied to yeasts. 



When the gypsum block cultures are left exposed for a long 

 time they become infested with all kinds of anuebie, which 

 gain access from the atmosphere and grow by devouring the yeast, 

 as was observed by P. Lixdxek (VI. and X.). In such event, 

 sporocysts, the permanent form of these aiiimalcul:e, can lie 

 discovered on the blocks. 



.!; 248.— Germination of Saccharoniycetes Spores. Their 

 Resistance to Heat. Pasteurisation. 



Reess (1.) was the lirst to observe the germination of Sar- 

 channnt/t'i'fi.-i ascospores, ami more extensive and prt'cise investi- 

 gations were afterwanls conducted by E. L'liH. Haxsen (X\'I1.), 

 whose reports constitute the 

 main basis of the information 



germination 



Firt. 144.— Sai-charomycesi-eri-visia- 1. Hansen. 



(ierniinatiou of spores. Kor explanation 

 soe t«'\t. Mngn. i.o^. {A/tfr Ilanxrn.) 



Speaking generally, the 

 of spores pro- 

 <'eeds in one of four dilTerent 

 ways. An example of the 

 first and most usual method 

 is afforded by Sarrh. rfreri.tid' 

 J. Hauai'ii. The ascospores 

 of this yeast are capable of 

 germinating as .soon as ripe, 

 unless prevented by unfavourable external cii cumstances. The 

 presence of water is an indispensable condition, large quan- 

 tities of this liquid, and of any nutrient substances present, being 

 taken uji by the geiininating spores, which thereujion swell \\\> 

 to a considerable size. If they are still enveloped bv the |>art'nt 

 cell, thi.■^ l.itter is stretched and assumes a .somewhat .angular 

 contour, as shown at Kig. \.\.\ at a and </. Tin- residual jilasnia 

 in the parent cell is compressed llat between the spores, but 

 reacts on the latter, and fm'ces them into a ]iolvhednil shape so 



