134 
Heligmosomum inuris Yokogawci 
Table I. 
Increases in Size of the Body of H. muris during the First Stage of Development. 
Specimen 
Length 
Width 
Buccal-cavity 
(depth) 
Oesophagus 
(length) 
Tail 
(length) 
number 
(mm.) 
(mm.) 
(mm.) 
(mm.) 
(mm.) 
1 
0-28 
0-015 
0-014' 
0-072 
0-052 
2 
0-300 
0-018 
0-012 
0-060 
0-06 
3 
0-395 
0-018 
0-013 
0-080 
0-08 
4 
0-419 
0-022 
0-013 
0-086 
0-09 
5 
0-442 
0-022 
0-013 
0-110 
0-09 
6 
0-560 
0-031 
0-014 
0-123 
0-10 
7 
0-640 
0-030 
0-0145 
0-131 
0-10 
8 
0-650 
0-032 
0-014 
0-116 
0-11 
9 
0-680 
0-032 
0-014 
0-125 
0-10 
10 
0-700 
0-033 
0-015 
0-127 
0-10 
11 
0-720 
0-035 
0-016 
0-125 
0-11 
Activity during first larval stage. The newly hatched larvae are small and 
move very slowly. After a few hours they move more actively and commence 
to feed. In the larvae at this stage a contraction of the intestine can be noted, 
causing a bulging of its posterior end. During the second day, the growth 
of the larvae is remarkable and constant movements are noted. Usually about 
two days after hatching when the chyle intestine becomes packed with granules 
the movements become somewhat slower. After this they start in on the 
first moult. 
(d) The First Moult. 
At the time of the beginning of the first moult, the chyle intestine appears 
to contain a great amount of refractive granular material. These granules are 
the globules of food material stored in the cells lining the intestine. These 
(Fig. 3, Plate VII) intestinal cells seem to be entering into a period of division, 
since many nuclei can be seen in them. This division of the cells proceeds from 
the anterior region backwards. Therefore the cells in the posterior region of the 
intestine at times will show no evidence of cell division, while in its anterior 
region this process is apparently going on. By this cell division, the cells 
lining the intestinal wall are modified into flattened cells containing fine 
yellowish brown pigment granules, and transparent ellipsoidal nuclei (Fig. 4). 
This cell division in the intestinal wall is a revolutionary process, since the 
cells do not increase in number. Those cells which jut into the lumen of the 
intestine break off after division and seem by degeneration to set free food 
material which is utilized during the moulting period. This revolutionary 
modification greatly increases the width of the intestinal lumen, which now 
loses its irregular zigzag character (Fig. 4, Plate VII). 
During the first moult, the constriction of the oesophagus becomes less 
marked and it loses its rhabditoid shape. Also a newly formed cuticula gradually 
makes its appearance. After a while the tail becomes separated within the 
old cuticula and the beginnings of the lateral bands of the new cuticula appear 
(Fig. 5, Plate VIII). The newly formed tail is blunter and shorter than during 
