May 3 ,1924 Dissemination of Tylenchus dipsad in Seeds 
475 
with ballast flora, considers this a very great probability. He is familiar with 
the early appearance of the plant in the Northwest, and with its very rapid 
spread and increase until now it is one of the most common and troublesome of 
lawn and meadow weeds. He referred me to Fort Nisqually, near Olympia, 
Wash., as the site of an early ballast dump, and the very possible point of intro¬ 
duction of the weed. True enough, in 1923 I found Hypochaeris in that vicinity 
in unusually great abundance as a roadside, lawn, and garden weed. Early 
settlers in that region stated to me that they knew when it first appeared, ap¬ 
proximately 50 years ago. 
The interesting observation was made as well, that the parasitic nematode 
Tylenchus dipsad was observed to be very abundant in that region, possibly 
even more so than where first observed in western Oregon, and certainly more 
abundant than in its southern range, in western California. It would appear to 
be very plausible to suppose that the parasite was introduced along with the host 
plant, and that the parasite as well as the host plant have become simultaneously 
widespread. 
CREPIS VIRENS 
While studying the flora associated with diseased Hypochaeris , I found a few 
typically affected plants of Crepis virens } first at Eureka, Calif., and later at 
Seaside, Oreg. They were by no means as abundant as affected Hypochaeris 
radicata f and merit attention only in the fact that they constitute a new host 
record for the organism. 
TARAXACUM OFFICINALE 
Stem-nematode-infested dandelions, Taraxacum officinale , were first encoun¬ 
tered at Williamson, in Wayne County, N. Y., in July, 1923. Subsequently 
they were found occasionally all the way between Ithaca and Niagara Falls, 
and across the Niagara River, in the Province of Ontario, Canada. Plant 
disease survey forces in the State eventually reported the disease to be present in 
14 counties in western New York. In September I found it among dandelions 
growing in a low meadow in Arnold Arboretum, in Boston, Mass. 
With the true dandelion, therefore, as with the false dandelion in the West, 
considerable distribution of the parasite has taken place. 
RELATION OF THE NEMATODE TO THE SEED 
When first observations were made on nematode-diseased Hypochaeris , the 
plant was not flowering, consequently the disease was to be found only in the 
leaves. (#, PI. 2). Later summer observations, however, disclosed the presence 
of swellings in the flower pedicels. The abundant occurrence of stem swellings 
due to an insect, Aulax hypochaeridis (PI. 1, A) were at first confusing. Char¬ 
acteristic nematode swellings became evident, however, usually in the pedicel 
at th'' _ of the flower head. These were irregular, resulting sometimes in 
considerable distortion, and were distinctly soft, rather than hard as were the 
insect galls. Typical blossoms in this condition, compared with the normal, are 
shown in Plate 1, B and C, As stated previously, the swellings pictured by 
Massalongo ( 9 ) are identical in appearance with these. 
Such affected stems of Hypochaeris when cut longitudinally showed brownish 
discoloration in the receptacle, and for a short distance below, in the pith of the 
stem. This condition is illustrated in Plate 1, D. The discolored tissue was 
found to contain an abundance of living, active Tylenchus in all stages of develop¬ 
ment. 
Flowers in various stages of development were studied. By microscopic 
examination it was seen that some of the very young seed were discolored at their 
