No. 33.] 217 
mer (Sib. 1883), also from report of 1883, Satisfaction Black Seeded 
(Sib. 1883), and Salamander (Hen. 1883). 
American Curled (Vil.), Prize Head (Sib. 1883), American Gather- 
ing (Sib. 1883), and Ferry’s Early Prize Head (Ferry 1883). 
«. lack Seeded Butter (Hen.), and Bloomsdale Butter, Black Seeded 
an.). 
Dwarf Green Early, Black Seeded (Greg.), and Very Early Dwarf 
Green (Vil.). 
Early Curled Simpson (Vil.), and Munson’s Perfection (Sib.). 
Green Paris Cos (Vil.), and Landreth’s Heat Resisting Cos (Lan.). 
Hardy Red Winter (Vil.), and Red Winter Cabbage (Thor.). 
Neapolitan (Vil.), Large Saint Angelo (Dam.), and New Giant of 
Salermo (Dam.). 
Very Large Yellow Paresseuse (Dam.), and Large White Stone 
Summer (Vil.), also from report for 1883, White Cabbage (D. 
Batchelor, 1882). | 
In a few cases lettuce described as distinct. by Messrs. Vilmorin, 
Andrieux & Co., showed no difference as grown by us. Thus the 
samples labeled Large Green (Vil.) and Large Green Pas-de-Calais 
(Vil.), seemed the same, also the Crisp Small Early Cutting (Vil.) 
and Crisp Small Early Frame (Vil.). A change of climate may have 
obliterated the slight variety differences. 
The sample labeled Improved Spotted, White Seed (Vil.) was 
evidently a mistake, as the plants produced were unquestionably 
identical with those of Marvel or Red Beson. é 
About the middle of July several of the lettuces were attacked by 
a mildew, which gradually spread until nearly all of the varieties 
were affected. Further notes upon this subject may be found in the 
report of the Botanist. We noticed also on August 4, that the 
roots of many varieties were attacked by aphides, which caused the 
foliage to droop as if suffering from extreme dryness. 
We noted an interesting fact in connection with the heading of 
lettuce. The tendency to form a head seems to be promoted by a 
certain degree of crowding. When the leaves of one plant do not 
touch those of its neighbor, they have a certain tendency to spread 
out, but when the plants are sufficiently close so that the leaves are 
compelled to grow upright, the inclination to form a head is evi- 
dently increased. ‘Too much crowding on the other hand tends to 
prevent the formation of the head. We noted in several cases that 
plants so remote that the leaves couid not touch each other, and those 
very close together, formed the flower stalk sooner than those which 
were just close enough so that the outer leaves were compelled to 
grow half erect. 
We made several experimental plantings of lettuce such as earliest 
and latest ripe seed, green and ripe seed, from upper and lower 
branches, but we could discover no differences in the crop that can be 
ascribed to any. particular selection of seed. 
We learned, however, that the flowers of lettuce do not cross-fer- 
tilize from natural agencies, to any marked degree. We grew ten 
[Assem. Doc. No.83. ] 28 
