GERMINATION OF ASCOSPORES 



31 



time, about one-half of the ascospores undergo this copulation ; the 

 others germinate by themselves without fusion. 



Second Example, Saccharomy codes: The ascospores of the genus 

 Saccharomy codes, which has been described for the first time by 

 Hansen in Saccharomyces Ludwigii, germinate in a somewhat special- 

 ized manner. As we have seen, the ascospores of this yeast are almost 

 constantly in the number of four in each asc. The wall of the asc is 

 able to break before the germination to free the ascospores. More 

 often they persist during the first phases. 

 Germination begins always by a swelling 

 of the ascospores. Whether these spring 

 from old or young cultures, has much to 

 do with the development. 



In the first case, the majority of as- 

 cospores, a little swollen, undergo a 

 copulation which has been described in a 

 preceding paragraph and upon which we 

 shall not dwell at this time. The asco- 

 spores, ordinarily united in ascs in which 

 the membrane is not broken, put out 

 a little protuberance by means of which 

 they unite two by two. The middle wall 

 by which they are separated rather 

 quickly disappears. Sometimes copulation 

 takes place slowly; the protuberances put 



out by each cell elongate and fuse at the Fig. 37. Germination of very 



Old Ascospores in Saccharo- 



myces Ludwigii. 



ends after having gone along together for 



some time. The ascospore then looks like 



a horse-shoe. (Fig. 37, a and c.) In some cases, one sees the fusion of 



three ascospores in the same asc in a single zygospore (Fig. 36, A). 



This, however, is very rare. 



The copulation of the ascospores being incomplete, the zygospore 

 is made up of two enlargements united by a copulation canal in 

 which is concentrated the nucleus and protoplasm. This commences 

 to germinate by a procedure intermediate between budding and 

 transverse division. The center of this canal elongates into a little 

 germination tube. This tube perforates the wall of the asc if it is 

 not already absorbed, until it swells in its upper part. This then 

 separates itself from the rest of the germination tube by a little 

 wall and a slight circular constriction. The cell formed in this manner 

 detaches itself from the zygospore, which forms new cells by the 

 same procedure. Sometimes, the first cell formed by the zygospore, 

 without detaching itself, gives birth to one or many more cells which 



