PHYTOPHTHORA 123 



The oospores measured 52-3 fi, epispore pale yellow. 



Peglioni finds that the dissemination of Sclerospora in 

 cereals is effected by the presence of mycelium under the 

 outer coating of the seed. Grains from a diseased head were 

 sown without any treatment ; some did not germinate, and 

 those that grew presented abnormal characters, and micro- 

 scopic examination showed the presence of mycelium in the 

 younger parts of the plants. 



Cugini, Le Stazioni sper. agrar. Ital., 35, p. 46. 

 D'Ippolito and Traverso, ibid., 36, p. 975, 996. 

 Peglioni, Atti Reale Accad. Lincei, 305, p. 509. 



PHYTOPHTHORA (De Bary) 



Conidiophores emerging through the stomata of the host- 

 plant, sparingly branched ; conidia ovate, papillate, produced 

 apically, producing zoospores. Oospores globose, epispore 

 rather thin, smooth, brown. 



The conidia or zoosporangia are in reality always acrogenous 

 or apical, but when a conidium is formed at the apex, the 

 conidiophore continues to increase in length, and bears 

 another conidium at its apex, and this continues repeatedly ; 

 consequently many of the conidia appear to be developed 

 laterally on the conidiophore. 



Trie potato disease. This terrible scourge, caused by 

 Phytophthora infestans (De Bary) was noted at Boston, U.S., 

 also in Denmark and Norway between 1840 and 1842, and 

 by 1845 ^ na d become general throughout Europe, doing 

 immense damage. It is perfectly certain that the disease was 

 imported to Europe, but why its advent was for so long 

 retarded after the introduction of the potato, is a problem 

 that cannot be solved. The same is the case with the holly- 

 hock disease. The disease is well known in South America, 

 the home of the potato. I observed it frequently in various 

 parts of Ecuador in the patches of potatoes cultivated by the 

 natives. Wherever the disease was introduced it appears 

 perfectly certain that it came in the form of hibernating 

 mycelium in the tubers. Oospores or resting-spores are 

 unknown, and the conidia germinate at once on reaching 

 maturity. Prillieux considers that when the potato was first 

 introduced, the long period occupied by the voyage, and 



