EUROTIUM 239 



B. From a culture of some six weeks' duration on dry bread 

 pick off with a needle some of the minute spherical perithecia : 

 mount them in water and examine under a low power; ob- 

 serve 



1. The round or oval form of the perithecia. 



2. That they are composed of a small-celled pseudo-paren- 

 chymatous tissue. 



3. Their yellow colour. 



4. Their insertion, each being borne on a single filament of 

 mycelium. 



The yellow colour is due to an oily substance, which is 

 soluble in alcohol, or in potash solution. 



Treat some perithecia with a weak potash solution, mount 

 them in glycerine, and examine under a high power : note 



1. The wall of the perithecium, consisting of a single layer 

 of somewhat flattened cells. 



2. The cavity surrounded by that wall, filled with bodies of 

 oval form the asci. 



In order to be able to examine the asci in detail, mount fresh 

 perithecia in glycerine, press with a needle on the cover-slip so 

 as to burst them, and note 



1. The ruptured wall, as before. 



2. The oval asci, each of which contains eight ascospores, 

 of oval shape when young, and biconvex-lens shaped when 

 mature. 



3. Other cells may also be found which belong to the pseudo- 

 parenchyma ; this is derived by ingrowth from the wall of the 

 perithecium, and is only to be found in young perithecia : at the 

 period of maturity it is completely absorbed. 



Among the Moulds which appear with constancy on bread 

 kept under a bell-glass, as also on other organic bodies, is 

 Penicillium : it may be readily distinguished from Aspergillus 

 by its lower growth, more velvet-like appearance, and blue-green 

 colour, while the latter shows a higher growth, so that the 

 individual conidiophores may be seen with the naked eye, and 

 its colour is an olive-green. 



Remove a small piece from a pure patch of Penicillium which 

 has been recognized by the above characters : tease it out with 



