744 



SCIENCE 



[N. S. Vol. XXXIII. No. 854 



difference in the physical or chemical composi- 

 tion of the soil. It was found, however, that 

 the mountain pine {Pinus montana) acted 

 as a nurse to spruce trees planted in its 

 vicinity. In the same soil where spruce if 

 planted alone would remain backward, it would 

 if planted close to a mountain pine grow up 

 vigorously. After some years of trial, it was 

 found that the pine would hamper the growth 

 of the spruce, and so it was cut down at an 

 early age. It was discovered then that even if 

 the mountain pine was cut down at an early 

 age, it imparted to the adjacent spruce 

 trees the ability to grow. The phenomenon 

 is not understood, but it is supposed that the 

 roots of the mountain pine are inhabited by 

 some mycorhiza which produces the nitrogen 

 necessary for the growth of trees and that this 

 organism is transferred to roots of the sur- 

 rounding spruce trees. Once this infection 

 has taken place, the presence of the mountain 

 pine is no longer necessary and it is usually 

 cut down. Clearly this is a biological rela- 

 tionship. 



John W. Haeshberger 

 Univeesitt op Pennsylvania 



SPECIAL AETICLES 



"^OOSPORES OF POTATO BLIGHT 



The potato blight fungus, Phytophthora 

 infestans, has attracted more attention from 

 botanists than almost any other fungus. The 

 reasons for this are that under certain cli- 

 matic conditions it causes sudden and wide- 

 spread destruction of potato fields, and also 

 that, though its life history has been carefully 

 studied, the sexual or oospore stage has never 

 been surely found. Berkeley, who was one of 

 the earliest investigators to have a rational 

 view of the cause of the epidemic of 1845, 

 wrote at the time as follows: 



Few subjects have attracted more attention or 

 have been more variously canvassed than the 

 malady with which potatoes have been almost uni- 

 versally visited during the autumn of 1845. The 

 press has teemed with notices the most contra- 

 dictory; the attention of scientific men in every 

 direction has been engaged by it; and three, at 

 least, of the principal governments of Europe have 



issued commissions to examine into its etiology, 

 and to discover, if possible, a remedy. 



In 1875-76, at a time of considerable de- 

 vastations of potato crops in Europe by the 

 fungus, DeBary was employed by the Royal 

 Agricultural Society of England to further 

 investigate this fungus, while at about the 

 same time Worthington G. Smith was en- 

 gaged in similar work for the Royal Horticul- 

 tural Society. As the result of their endeav- 

 ors, considerable was learned concerning the 

 life history of the fungus. Smith claimed to 

 have found the oospores in the infested leaves 

 and the old sets in great abundance, and was 

 awarded a gold medal by the Royal Horticul- 

 tural Society for his work. These bodies had 

 been observed as early as 1845 by Rayer, Mon- 

 tague and Berkeley. DeBary did not succeed 

 in finding what he considered oospores of this 

 fungus, and disputed Smith's claim with such 

 good reasons that botanists generally believe 

 that the oospores have never been discovered, 

 though once or twice since investigators have 

 claimed, without much conviction, to have 

 found immature oogonia. 



At the time of the controversy DeBary 

 said: 



Ever since the oospores of a Peronospora were 

 discovered, innumerable researches have been made 

 for those of PhytopJitlwra, I have myself looked 

 for them for fifteen years, and on every oppor- 

 tunity have searched for them in the stalks, leaves, 

 flowers, fruit and tubers of the potato. In July 

 of the present year (1875), when the fungus ap- 

 peared in this district in sad abundance, I ob- 

 tained a very large amount of material for study, 

 and at the same time secured the kindly assistance 

 of two botanists experienced in researches of this 

 kind. Dr. Eostafinski and Dr. Stahl. But again 

 only negative results were arrived at. . . . That 

 they will be regularly found somewhere or other 

 is assured, for our knowledge of the habits of 

 numerous allied fungi make this more than prob- 

 able. 



Smith deposited slides of his oospores with 

 the British Museum. Concerning these Mas- 

 see some time ago wrote me : 



I have very carefully examined W. G. Smith 's 

 type slide preparation, and am positively certain 

 that the so-called oospores are nothing more than 



