196 MYCOLOGY 



EndophyUum sempervivi which attacks the house leek, Semper- 

 vivum, and causes its rosette of normally spreading leaves to stand 

 erect, shows a somewhat different condition, which has led to the sup- 

 position that it represents the primitive life cycle of the higher ure- 

 dineous fungi. Its life history has been investigatecl by Hoffman 

 (191 1). The spores mature on the house-leek leaves in April and 

 May. They germinate at once in the secidioid telium and a four- 

 celled basidium is formed; hence, the spore looks like an seciospore 

 and partakes of the nature of a teliospore and may be called an secio- 

 teliospore. Each basidium produces four basidiospores on long sterig- 

 mata, and they are blown to the leaf of a house leek, where they 

 begin growth at once by boring through the cuticle, and the mycelium 

 then grows through the intercellular spaces of the host sending haus- 

 toria into the cells, growing down to the base of the leaf and into the 

 axis up to the growing point, where it perennates until the following 

 spring, when it enters the freshly formed leaves, which become yellow, 

 longer and more erect. 



Pycnia are formed in March and April followed by aecio-telia, 

 which repeat the cycle. Hoffman has established the most interest- 

 ing point about this rust, that the aecio-teliospore chain arises from a 

 cell produced by the fusion of two adjacent cells of the spore bed 

 after the manner described by Christman except the conjugating cells 

 were not in any definite plane. The binucleate secio-teliospores then 

 become uninucleate by the fusion of the conjugate nuclei. The for- 

 mation of the basidiospores from these oecio-teliospores probably 

 follows a reduction division. 



Kunkel (191 4) has shown that a study of the binucleate seciospores 

 of CcBoma nitens during germination shows that they become uninu- 

 cleate previous to the production of the promycelia. The normal ger- 

 mination of the aecio-teliospore consists in the pushing out of a germ tube 

 into which the protoplasmic contents of the spore passes. The nucleus 

 which travels out into the tube divides producing two nuclei which may 

 divide again immediately and cell division may follow at once, but in 

 other cases the four nuclei of the promycelium (basidium) may be 

 present before cross walls are formed. Ultimately, four cells are found 

 filled with protoplasm and uninucleate. The basidiospore arises as an 

 enlargement of the sterigma and the nucleus enters when it is one-half 

 developed. Cceoma nitens although like EndophyUum sempervivi in 

 some respects is more primitive, since it possesses a simpler aecium. 



