1912] Anatomy of Tomato-worm Larva 257 
and disappear from view in the extreme caudal part of the 
preceding abdominal segment. Other muscles besides those 
thus far discussed are present in each body segment. By care- 
fully lifting the longitudinal fibres, one finds other bands of 
muscles running at an angle to those named above. This is 
indicated in Fig. 12, (x), where in the caudo-dorsal angle of the 
free part about the spiracles in each segment one sees the ends 
of such diagonal bands. 
CIRCULATORY SYSTEM. 
Dorsad of the alimentary canal is a long slender tube 
(Fig. 12) embedded to some depth in a mesal cavity of adipose 
tissue between the right and left bands of the great dorso-recti 
muscles. This tube, which comprises the whole of the enclosed 
circulatory system, extends from the eighth abdominal segment 
to and within the head. The enlarged part of this tube, 
extending from the eighth abdominal segment into the meta- 
thoracic region, is the pulsating organ, the heart. 
Heart.—The heart (h) is a very delicate, flattened, muscular 
tube closed at the caudal end and presumably opening in each 
segment by a system of valves. Owing to the lack of fresh and 
living material the valves of the heart were not studied. After 
injecting some colored fluid into fresh specimens, the valves 
should readily show themselves. 
Wings of the Heart.—Within the area of the first to the fifth 
abdominal segments, four pairs of laterally extending fan-like 
rays of tendons (w. h.) are seen. The tendons extend from the 
ventro-lateral edges of the heart and converge at the point 
where the three anterior dorso-ventral muscles penetrate 
between the great dorso-recti muscles and the small dorso-recti 
muscles. The wings are composed of connective tissue and 
muscle fibres, connecting themselves to the body wall beneath 
the small dorso-recti muscles. The function of the wings of the 
heart is probably to protect the heart from the peristaltic move- 
ments of the alimentary canal. Between successive fans the heart 
proper is distinctly constricted. In these regions without 
much doubt the valves of the heart are located. The caudal 
part of the heart, extending from the midportion of the fifth 
abdominal segment to the caudal end, is supported by scattered, 
irregularly arranged tendons on the ventral surface, that attach 
themselves to the nearby body wall. 
