118 



Mycologia 



and still retain the power of infection. The expressed juice of 

 mosaic plants rarely remains infectious longer than 24 to 48 

 hours, and the virus is rapidly destroyed by desiccation. The in- 

 fective principle, as far as it has been determined, possesses many 

 properties of a living organism, and it appears possible that the 

 disease may be caused by an ultramicroscopic parasite. The 

 mosaic is highly infectious and can be produced by introducing 

 the expressed juices or crushed tissues of a mosaic plant into 

 slight wounds in healthy plants. 



Volume 10 of North American Flora 



The first three parts of this volume were issued some time 

 ago. The manuscript for part 4, prepared by Kauffman and 

 Overholts, will be ready for the printer within a few months. 

 Part 5 will be chiefly devoted to Cort'marius, to be treated by 

 Kauffman. Part 6 will continue the brown-spored and black- 

 spored agarics; and part 7, the gasteromycetes and an index, 

 concluding the volume. 



Specimens of gill-fungi with brown or black spores, or any 

 of the gasteromycetes, will be very gladly received from myco- 

 logical friends. I do not care for Poria at present ; this group 

 will have to wait until volume 8, containing the Thelephoraceae, 

 Clavariaceae, Hydnaceae, etc., is well started. 



The determination of miscellaneous collections of the higher 

 fungi must take second place with me henceforth, as my time 

 for scientific work is limited. I have enjoyed this kind of work 

 immensely during the past twenty years, and a vast number of 

 interesting things have been added to the herbarium through 

 collections sent in from widely separated localities. 



If collectors wish to deposit sets of their larger fungi here 

 without expecting reports until the various groups are worked, 

 such specimens will be welcomed. In the case of special plants 

 sent in for critical examination, please mention the species with 

 which you would have them compared and also give microscopic 

 characters, so as to facilitate comparison as much as possible. . 



W. A. MURRILL 



Supervisor of Public Instruction 



