Vol. 41 No. 9 
BULLETIN 
OF THE 
) TORREY BOTANICAL CLUB 
a ee en 
SEPTEMBER, 1914 
; A review of investigations of the mosaic disease of tobacco, to- 
gether with a bibliography of the more important contributions 
: H. A. ALLARD 
Concerning the nature of the mosaic disease, many important 
a facts have been published from time to time, both in America and 
in Europe. However, from the published accounts of earlier 
investigators, especially in Europe, it is now known that various 
pathological appearances entirely distinct from the true mosaic 
have been ascribed to this disease. In reviewing the literature 
of the subject one is at once impressed with the contradictory 
conclusions reached by different investigators and the conflicting 
results frequently obtained in their individual experiments, which 
oftentimes indicate that the controls were quite as subject to the 
disease as plants inoculated with the virus. Unquestionably, 
= these discrepancies to a great extent can readily be accounted 
v: for in the light of facts recently brought out by the writer (59, 
64)* regarding insect agencies which may become active dis- 
seminators of infection and which have heretofore been overlooked 
in a study of the disease. 
After several years of careful investigation, Iwanowski and 
Polowzoff (4) concluded that the term ‘“ Mosaikkrankheit’’ had 
frequently been used to cover two very distinct diseases, i. e. 
true, infectious mosaic and ‘‘Pockenkrankheit.’”” Mayer con- 
sidered ‘‘ Pockenkrankheit" simply a later phase of true mosaic 
and thus associated the two diseases under the term “Mosaik- 
* The dosiay numbers in Mpeg on in tibia paper putes to the ‘ tindex to 
the literature of mosaic,’ 
{The BULLETIN for i pi 391~434. pl. 15-20) was issued 25 Au 1914] 
435 
