296 ETTROTITTM. 



427. Development of Gonidia. Examine young por- 

 tions of the mycelium, which have not yet become coloured 

 by the ripening goiiidia. 



Note that (1) the gonidiophore arises as an unbranched 

 stout hypha, close to a transverse wall on a mycelial hypha 

 and containing distinct granular vacuolated protoplasm 

 and numerous nuclei; (2) the free end of the gonidio- 

 phore swells up, but is not cut off ; (3) from the enlarging 

 head there grow out numerous papillae, the sterigmata ; 

 (4) each sterigma elongates, and then becomes skittle- 

 shaped, an oval or spherical gonidium being budded off 

 from its tip ; (5) after the first gonidium has grown in 

 size, a second is abstricted from the sterigma, just below it, 

 in the same way, and so on until a chain is formed. Be- 

 fore each budding occurs, nuclei pass into the developing 

 gonidium, which when mature has about four nuclei ; the 

 gonidium has a distinct but rather thin wall, which con- 

 tains the greenish pigment (not chlorophyll) that gives 

 Eurotium its colour. 



428. Germination of Gonidia. Boil some prune or 

 plum decoction, and make a hanging-drop preparation with 

 a few goiiidia, as directed for Mucor ( 422) ; the germina- 

 tion and the formation of the mycelium take place as in 

 Mucor, except that in Eurotium 'the mycelial hyphae are 

 from an early stage onwards septate owing to the nume- 

 rous cross-walls formed. 



429. Structure and Development of Ascocarp. 



To observe the ascus-fruits, or ascocarps, keep some bread 

 dry for a month or more; when ripe the ascocarps are 

 easily seen with naked eye or lens as yellow spherical 

 structures. Some of the stages in the development of the 

 ascocarp may be seen on examining some Eurotium which 

 has already produced gonidiophores ; mount in alcohol, 

 add water, and tease out with needles. 



Two simple methods may be used to induce the forma- 

 tion of sexual organs and ascocarps. (1) Transfer some 

 gonidia to a piece of bread soaked in 40 per cent, cane- 

 sugar solution in prune juice, and keep at about 30 C., 



