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color also grow there. Salix. sericea grows in the immediate 
vicinity, but has not been detected in the bog. Stations for S. 
petiolaris are known not far from the bog, and it is highly probable 
_that both the species last mentioned grew in the bog before vege- 
tation was disturbed by settlements. 
In the spring of 1894 several forms of Salix candida were 
brought into the laboratory, one of which was so unusual in its ap- 
pearance that specimens were sent to Mr. Bebb. These speci- 
mens were from the plant labeled No, 20. Of it in a letter he 
said, “just at a glance, without a careful examination of minute 
characters I should take your smoother form to be a hybrid, 
Salix candida X S. petiolaris. In addition to the differences from 
pure candida which you mention, you will observe that the aments 
are borne on slender and more distinctly leafy peduncles. I 
imagine too that they are more loosely flowered. The capsules 
are too old to afford a good view of the style (without soaking up, 
for which I have not the time at present), but I fancy it is shorter 
than pure candida. The leaves have a different outline, being 
Mure pointed at base, and exhibit (even in your carefully dried 
Specimens) a slight tendency to blacken, and the margin is less dis- 
tinctly revolute. It would not be well to rest a decision on the 
scant material before me, but I have very little doubt that if you 
carefully study the forms in the locality from which this specimen 
was obtained, in flower, fruit and mature foliage, you will find con- 
vincing proof of hybridity.” 
Subsequent studies of these specimens during the same sum- 
mer convinced us that there was a very interesting series of forms 
in the bog, and in the spring of 1895 a systematic study of them 
was undertaken. The opportunity for observing the forms is es- 
pecially favorable, since the whole bog comprises not more than 
two acres, and the plants in question were all upon one corner of 
this area. Each individual which promised any appreciable varia- 
tion from typical forms, as well as a number of apparently typical 
forms, was given a number and marked with a tag. At the same 
time a map of the locality was made as a check and as a matter of 
convenience in finding our plants. Observations were made at 
frequent intervals, and specimens were taken at three periods dur- 
ing the season: First, at anthesis (April 30); second, when the — 
