Pomona College Journal op Economic Botany. 317 



were most often formed at the extremity of short, thin, lateral branches of 

 mycelium, but sometimes they were formed sessile on a filament. The mature 

 chlamydospore is distinguished by its roughened surface ; it is either white or 

 of a light, yellow, brown color. In cultures exposed to the cold of winter 

 certain mycelium filaments developed an elongated chlamydospore 30 u.- 

 35 u. in length by 18 u. in diameter and with three or four cross septa. These 

 chlamydospores germinated in sixteen hours in distilled water at a temperature 

 of 22° C. In germinating they produced one or perhaps two filaments which 

 perforated the exospore and were covered by the endospore. Very rarely a 

 germinating chlamydospore produced a secondary spore which was round, 

 yellow, thin walled and 9 u.-lO u. in diameter. No further studies of the 

 secondary spores were made. The life of a chlamydospore does not appear 

 to exceed a year. In one culture upon potato eleven months of age, the 

 minority of the chlamydospores germinated. Mr. L. Mangin and Mr. E. 

 Prillieux gave to this imperfect Ascomycete the name Fusarium dianthi. 

 Later Mr. L. Mangin made further studies in which he demonstrated the 

 parasitism of several species of Fusarium, including F. roseolum, F. commu- 

 tatum, F. roseum., F. anraiitiacum, F. oxyspomm and F. pyrochroum. He 

 concluded that the Fusarium of the carnation so closely resembled these 

 other species that it should not be given a separate name. 



Further observations in the field revealed that the disease was not of an 

 infectious character, for diseased plants were often found isolated among 

 healthy ones. The disease appeared to be a constitutional one, and some 

 horticulturists made the remark that their plants were suffering from tuber- 

 culosis. The disease appeared to develop most rapidly at the time when the 

 plant began to flower. In the examination of plants where the disease had 

 just started, Mr. L. Mangin found mycelium bearing conidia in shoots abso- 

 lutely healthy in appearance. Carnations grown under glass were more subject 

 to infection than those grown in the free air, but plants grown under any 

 condition were more or less subject to the disease. 



The ordinary method of propagating the carnation was by means of cut- 

 tings and these seemed to be a source for the transmission of the disease. To 

 prevent the spread of the disease in this way only cuttings from healthy 

 plants should be used. In order to recognize these the prepared cuttings may 

 be placed in the holes of a perforated board or metal plate and suspended over 

 a vessel of water in such a way that the base of the cuttings will be two or 

 three centimeters from the surface of the water. At the end of twenty-four 

 hours at a temperature of 50° C, the ends of the diseased cuttings will be 

 covered with a white mycelium, while the healthy ones will not .show any 

 infection. But to prevent the growth of any spores which may have lodged 

 upon them, they should be washed in a weak solution of copper sulphate; 

 one or two grams per liter may be used. 



Another source of infection was by means of wounds, in which nema- 

 todes and spiders had an important part. The discovery of chlamydospores 



