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338 BACTERIA IN RELATION TO PLANT DISEASES. 
varieties to attack. He obtained lists of sensitive and resistant varieties from seven 
growers. A study of these lists showed a very general agreement upon the following 
varieties as very susceptible: 
Snowball, single white; De Candolle, single blue; 
Grand Lilas, single blue; ; Princess héréditaire des Pays-Bas, single white; 
La Tour d'Auvergne, double white; Grand Vainquer, single white; 
Duchess of Richmond, single red; Mimosa, single blue; E 
L’Ornement de la Nature, single red; Alba Maxima, single white; 
Orandates, single blue; John Bright, single blue; 
Mirandolina, single white; 
The following varieties were regarded by the same growers as resistant, or only slightly 
susceptible: 
Pieneman, single blue; Argus, single blue; 
Norma, single red; Bleu mourant, single blue; 
Pucelle d’Orleans, single white; Willem I, single blue; 
Voltaire, single white; Maria Catherina (Robt. Steiger), single red. 
These two lists are copied from Wakker’s French paper published in Archives néer- 
landaises. 
In 1906 two of the leading hyacinth growers of Holland, men who have been in the 
business many years, were good enough to go through their catalogues and mark off for me, 
independently, varieties ‘‘much subject” to Bacterium hyacinthi, and varieties “very resis- 
tant,”’ leaving those varieties unmarked which are intermediate in resistance, or about 
which there might be a difference of opinion or a lack of exact knowledge. In this way I 
obtained information concerning about 300 varieties. I have carefully compared the two 
lists and find them flatly contradictory only in the case of three varieties—single red Pélissier, 
single rose Maria Cornelia, and single white L’Innocence. There are, however, numerous 
discrepancies, many varieties being marked + or o by one grower and left unmarked by 
the other. This might mean either entire lack of knowledge, or difference of opinion. In 
case it were disagreement we might assume either difference of behavior on the part of 
particular varieties in the hands of different growers, something not improbable, or that 
one man is a closer observer than the other. Of course if a variety is much subject to the 
disease in one field and resistant to it in another, the observed resistance might be entirely 
a matter of accident and not due to any strongly inherent peculiarity, of which one might 
take advantage in cross-breeding or selection. Varieties to the number of 130 were marked 
+ or o by one or other of the two growers, 73 as much subject to the disease, and 57 as 
very resistant. One grower reported 59 varieties “‘much subject” and 43 “very resistant,” 
the other reported 22 varieties “much subject” and 32 ‘‘very resistant.’’ The agreements 
are of greater interest. There are 26 of these, a number apparently too large to be purely 
accidental. In addition it should be mentioned that a number of the older varieties, marked 
+ in one catalogue, are not included in the lists of the other dealer, but must at one time 
have been grown by him, and may have been discarded on account of disease. The writer 
started inquiries to determine this point and found this supposition correct. Including 
these, also, the number of agreements is 35. 
The writer subsequently received a catalogue from a third large grower, a person well- 
known in the trade for thirty years or more. This man marked 61 varieties “much subject”’ 
and 13 varieties ‘‘very resistant.’’ The varieties concerning which this third grower is in 
agreement with the other two growers are marked with an asterisk in the following table. 
Respecting the other varieties in this table he makes no statement. He is in contradiction 
with one or other of the two growers, never with both, respecting the susceptibility of three 
varieties: Clio, single light blue; Obelisk, single yellow; and Czar Nicholas, double rose. 
He reported on 41 varieties not mentioned by the other growers, 5 being marked as 
resistant. 
The varieties concerning which the two growers agree are included in the following 
lists: The starred varieties represent the agreements subsequently received from a third 
large grower. 
