26 
The head varies from a form like Plates XVII, 3, 4, 7, 9, and XVI, 9, 
12, 13, 14, to that shown by Plates XVI, 10, 11, 15; XVII, 2, 5, 8, and 
XVIII, the neck from a mere contraction of the body, Plates XVII, 6, 
and XVI, 15, to a long tube, as in Plates XVI, 14, and XVII, 9. 
The body varies from almost a globe (Plate XVI, 9, 13) to an oval 
(Plate XVI, 14; XVII, 9), or nearly a cylinder. (Plate XVI, 15.) 
The worms found in woody tissue are usually of the forms of Plates 
XVI, 10, 11, and XVII, 5, 8 ; in soft tissues like Plates XVI, 14, and 
XVII, 7, 9, but I am unable to understand the reason of this variation. 
In roots, as a rule, the bodies radiate from the central axis of the 
root with the " heads " to the axis. 
When once enlargement of the body begins, the worm becomes a fix- 
ture, and remains incapable of progression in any direction; the en- 
largement is gradual and the cells of the root tissues become smaller 
by the pressure, forming a rigid wall on every side of the worm. 
How long the worm exists is an unsolved problem which I hope to 
solve in time. 
Apart from vegetable tissues, I have noted signs of life in the An- 
guillula after being kept air- dry six months, but have no record of any 
reliable experiments with the worms in the roots ; but the vitality is 
very great. 
When motion is first perceived in the cyst, the worm is an average 
of yiHHfo i ncn i n length and To"!™ extreme thickness ; soon after it be- 
comes free it enlarges and lengthens till it casts its skin, which it does 
as shown in Plate XI, 5, leaving the old skin shrunken as at 0, same 
plate; a fragmentary cast is seen on Plate XII, 1, but J have not de- 
termined the number of times in its life it sheds the skin, as it is rare 
to find a perfect cast for measurement. 
Among the thousands of Anguiilulae I have examined, there are a great 
many variations and arrangements of cells that are not easily explainable. 
Plates XV, XIII, and XII, 5, 8, 7, 6, exemplify some of the most marked. 
Plate XIII, 2, 3, is very singular; a cyst-like form, with segments. 
Also at 3, a peculiar arrangement of cells, large and small ; in fact, I 
have never found two worms exactly similar in the grouping of cells; 
the resemblance is general, but with wide variation of details. The ex- 
amples given in the plates justify this conclusion, sketched as they were 
from living specimens. 
The arrangement of the cysts in the uterus is generally as shown by 
Plates XVIII, XIX, and XX, though that often becomes changed, as 
indicated in Plate XXI. (Note 13.) 
In mature and apparently aged worms, I have found as many as a 
dozen free worms within the uterus, having attained motion and liber- 
ation there. 
In plates showing the changes in vegetable tissues, "A" refers to the 
enlargements and nests of Anguillulre, " P> " to spots of decay. 
