g6 Elementary Biology. 



So far, it would seem that we have to deal with a plant 

 very different in life, history from such a form as Fucus. In 

 the above account we have nothing comparable to the 

 spermaria and ovaria and their contents ; the two plants 

 have only a thallus in common. More careful observation, 

 however, discovers that we have by no means exhausted the 

 life-history of Penidllium. 



If the mycelium be placed under such conditions that 

 oxygen is partially excluded, whilst the cultivation goes on 

 in darkness, spore-bearing filaments after a time are not 

 formed so plentifully, and the budding off of spores comes 

 consequently to an end. In place of these, minute yellowish 

 bodies make their appearance the so-called ' fructifica- 

 tions.' It will conduce to clearness if we trace the de- 

 velopment of these ab initio. 



The first stage in the formation of a * fructification ' is the 

 spiral coiling of the terminal cell of one of the threads of the 

 thallus (fig. 28, A) ; the spiral coil so formed is a close one, 

 and the cell becomes by transverse partitions divided into 

 as many cells as there are turns in the spiral. At the same 

 time a small branch from the same terminal cell grows up in 

 a spiral manner round the other spiral and closely intertwines 

 itself with it. Ultimately fusion of the two spirals takes 

 place and the protoplasmic contents mingle with each other. 

 After fusion of the two spirals, a series of filaments spring 

 out from the parent filaments from which the spirals arose, 

 which enclose and protect them. In some forms of mould 

 very elaborate capsules are so formed. In Penidllium the 

 surrounding envelope closely embraces the spirals and is 

 of a spongy texture, owing to the continuous growth and 

 division of the enveloping filaments. The chief or primary 

 spiral, however, after fusion with the secondary spiral 

 develops branches (0.rcz)which push their way in amongst the 

 enveloping filaments. At this stage the mass (already re- 

 ferred to above as the ' fructification ' ) becomes detached 

 from its thallus and may undergo further development either 



