154 SUMMARY OF CURRENT RESEARCHES RELATING TO 



the main stems of seedlings and saplings of western yellow pine (Pinus 

 ponderosa) in California. On one of the saplings Eecidia had already 

 formed spores, while on another the spores were exuded from the- 

 pycnidia in Brazil-red drops. The infected seedlings grew in close 

 proximity to Comandra itmhdJata, which bore the uredospores and 

 teleutospores. From various observations he concluded that the secidia 

 do not develop until the season following the appearance of the pycnidia. 

 A. Bucheim * found a specimen of Melampsora Lini towards the 

 end of April at a height of 1300-1400 m. The uredospores were 

 growing close by the previous year's teleutospore sorus, and he con- 

 sidered that the uredo must have developed from the mycelium that 

 had wintered in the host-plant. Infection experiments gave a series 

 of forms on other species of Linum. 



Histology of Californian Boletaceae.t — H. S. Yates has undertaken 

 a research on the structure of all the species of Boletus growing in 

 California, his object being to extend as far as possible the knowledge 

 of these species, to determine the details of individual species, and to 

 compare the histology of one with another. 



All of the Californian Boleti are terrestrial, and probably saprophytic 

 on decaying leaves . and twigs, and they all inhabit woods ; none were 

 found in op3n fields. Yates explains the general structure, and then 

 gives details of the structure of each species, with special reference to- 

 the rind of the pileus and stipe and the structure of the pores. 



Contribution to Fungus Biology. f—G. H. Coons gives the result 

 of culture experiments with Plenodomiis fascomacuJans, a fungus 

 parasitic on the apple^ The problem to be solved was the determination 

 of the effects of various controlled factors upon the growth and 

 reproduction of the fungus. It was found that there was a wider 

 range of conditions advantageous to growth than there were to 

 reproduction. Pycnidia, for instance, were not found in the dark, but 

 when their growth had begun in the light they would continue to 

 develop in the absence of light, though not so vigorously. " There is 

 therefore an inverse relation between growth and reproduction, 

 insomuch as a strong light inhibits the normal development of 

 mycelium." Again, pycnidia formed at temperatures between 10° C. 

 and 30° C. At lower temperatures pycnidia do not appear, though 

 mycelium still grows. 



Oxygen is indispensable for the growth of both mycelium and 

 fruiting bodies. Humidity delays but does not entirely suppress 

 pycnidial formation, while it is distinctly favourable to the mycelium. 

 More food is also required for reproduction than for vegetative growth. 

 A favourable culture medium for inducing pycnidium-formation was a 

 weak solution of magnesium sulphate and potassium acid phosphate in 

 combination with maltose and asparagin. 



* Arch. Sci. Phys. Nat., ser. 4, xli. (1916) pp. 149-54. See alsoBot. Ceutralbl. 

 cxxxii. (1916) pp. 139-40. 



t Univ. California Publications (Bot.) vi. No. 10 (1916) pp. 221-74 (5 pis.). 



X Journ. Agric. Research, v. No. 16 (1916) pp. 713-69. See also Bull. Agric. 

 Intell. Rome, vii. (1916) pp. 749-51. 



