27(5 ANOMALIES OF DEVELOPEMENT. CHAP. V. 



Accounted Du Hamel accounts for the anomaly of the flat- 

 tened stem by supposing that an unnatural graft 

 must have taken place in the leaf bud ; and so 

 united shoots that would otherwise have been dis- 

 tinct. But if shoots should be thus united by 

 means of an unnatural graft, why should they be 

 compressed or flattened in their aggregate growth. 

 Affected Sometimes the stem is disfigured by accidental 

 o/bunches! tumors or bunches projecting from the surface, and 

 forming ultimately what are called knots in the 

 wood. They are very common in the Oak and 

 Elm, and are produced perhaps by means of some 

 obstruction in the channel of the sap's motion, by 

 which the vessels become convoluted and swell up 

 into a bunch. 



But bunches are also to be met with on the stem 

 of herbaceous plants, as on that of the Carduus 

 pr at crisis ; of which you will often find a portion 

 near the top swollen out into an egg-shaped or egg 

 oblong bunch extending from an inch to two inches 

 in length and about an inch across. If this bunch 

 is cut open in the month of August, it will be 

 found to contain several large and white maggots. 

 It has consequently been occasioned by the punc- 

 ture of the parent insect depositing its eggs ; but 

 it does not seem to affect the general health of the 

 plant. Sometimes a number of trees growing 

 together are affected with a longitudinal protu- 

 berance all on the same side. This Du Hamel 

 attributes to a Coup de soldi vif, or to .frost. Some- 



