4 Karl Hermann Fernow 



types appear very different on the potato, the writer was not able to dis- 

 tinguish any difference in the symptoms on other species when inoculated 

 from potato. 



C. Mosaic Datura Stramonium L. plants sent to the writer by Dr. 

 A. F. Blakeslee from Long Island. 



D. A Nicotiana glutinosa L. plant which developed mosaic after inocu- 

 lation from a Datura Stramonium plant affected with mosaic C. While 

 this would seem to indicate that mosaics C and D are identical, the data 

 on this point are rather inconclusive and it seems better to regard these 

 mosaics as distinct until proof can be furnished that they are identical. 



E. Phytolacca decandra L. plants grown from roots of mosaic plants 

 dug near Tully, New York. In all cases the inoculum was taken from the 

 original plants. 



F. Mosaic Rumex obtusifolius L. plants found near Ithaca and trans- 

 planted to the greenhouse. 



G. Mosaic Phaseolus vulgaris L. plants grown in the greenhouse from 

 infected seed. Inoculum for the field experiments was taken from plants 

 of unknown variety growing in experimental plots. 



H. Mosaic EcJrinocystis lobata (Michx.) Torr. & Gray plants growing 

 outdoors in Ithaca. 



Plants inoculated 



The species selected for inoculation were chosen for various reasons. 

 Some were used because of their relationship to affected plants available, 

 or because of mention in literature. It was naturally impossible to work 

 with a large variety of species. Certain species were discarded because 

 of difficulty of culture or the failure to obtain infection. 



Except in the case of potatoes, all the plants used were grown from seed. 

 Special efforts were made to keep the plants growing vigorously by fre- 

 quent repotting. It was found that some species grew so slowly in the 

 short days of winter that they were not satisfactory for inoculation. 



The only inoculations made out of doors were made in the summer of 

 1923. The plants were started in the greenhouse and transplanted to the 

 field, being spaced three feet each way and one row of sixty-six plants of 

 each species being grown. Some species were repeated. 



It was thought that more reliance could be placed on results obtained 

 repeatedly with a relatively small number of plants, than on results 

 obtained with a larger number of plants all inoculated on one date. It 

 seemed desirable also to make the inoculations with different mosaics 

 on the same species on the same date, so that the results would be com- 

 parable. As space did not permit the growing of very large numbers of 

 one species at one time, it was necessary to reduce the number of plants 

 in .each experiment. In some cases this was doubtless carried to too 

 great an extreme, as when a single plant was inoculated from each source 



