Lecture XI! I. \ " V \ 



bends, which give rise to chains of ovoid cells the asci. In 

 each ascus eight ovoid cells, ascospores, are found. In addition 

 to the hooked branches the ascogenous hyphae produce narrow 

 tubular branches which penetrate into the inner layers of the 

 envelope. These tubular branches seem to have the function of 

 absorbing the materials proteins and cellulose stored in the 

 inner layers and of transferring them to the developing ascospores. 

 Not only are these cells absorbed, but even the ascogenous hyphae 

 and the walls of the asci are dissolved, so that finally only the outer 

 brownish-yellow wall of the envelope containing the ascospores 

 is left. The envelope of this fructification or ascocarp cracks 

 open when it dries and the ripe ascospores are set free. The 

 formation of the ascocarp from the production of the gametangia 

 to the liberation of the ascospores takes from six to eight months. 



The ascospores have a diameter about twice that of the conidia. 

 They germinate on moist organic surfaces by cracking open the 

 outer yellow layer of their cell-wall and pushing forth an outgrowth 

 which develops into a mycelium. 



Penicillium may be found growing on a great variety of organic 

 substances and hence is a very common plant. This shows that 

 it can supply its needs from a large number of different materials. 

 It is in fact omnivorous. Apparently this adaptability is closely 

 connected with its great wealth in enzymes. Probably from no 

 other plant have so many enzymes been isolated as from the 

 subject of our study. Penicillium has been shown to use diastase 

 for liquefying starch and converting it into maltose, cytase for 

 rendering cellulose soluble, invertase, inulinase and zymase for 

 breaking down other carbohydrates ; it has emulsin for glucosides, 

 protease and casease for attack on proteins, lipase for fats and 

 catalase which sets oxygen free from peroxides. It is probable 

 that a further search would bring to light a still larger variety of 

 enzymes in the repertoire of this extraordinary plant. 



By these enzymes it is enabled to draw the carbon it requires 

 for its growth and respiration from proteins, carbohydrates, fats, 

 organic acids and alcohols. 



Notwithstanding its omnivorous character Penicillium preserves 

 a refinement of discrimination which would do credit to the most 

 experienced epicure. This discrimination is strikingly shown in 

 its attitude towards tartaric acid. 



Pasteur found that when Penicillium grew in a nutritive solution 

 containing tartaric acid, the acid which before was optically in- 

 active became optically active. That is to say, it acquired the 

 power of rotating the plane of polarisation of a beam of polarised 



