Abstract
This paper intends to report three behaviour patterns manifected by individual and interrelation between them.
The aggregation of worm is performed succeedingly with three periods as primary, middle, and end period in an hour or so.
In the primary period, each individual works actively with swing movement of frontal two segments. At first, the worm does'nt move from proper situation, but after a few minutes, it moves as if to catch the direction of comming ordor stimulus, and approaches to the other individual to become contact with it. After they have contacted, they show a posture as they had recognized each existence by their appendages of the head such as antennae, maxillary palpi and thoracic legs. These appendages are used to do main role for keep them in continuous contact. This primary period generally appears in beginning to 10∼20 minutes, and lasts within 30 minutes.
The next middle period is not clearly expressed with time. This period belongs to a growing phase of two individuals to become larger groups. In this period each individual moves very actively crossing or mounting their body each other with minute action of the appendages of head and thoracic legs. The middle period lasts in very short time and soon enters to the end period.
The end period is a time of stabilization of the final group in which individuals become almost immobile. They take a resting posture keeping up their head part or frontal two segments and extending their thoracic legs frontward. After they fall in the resting condition, the internal physiological processes seem to go very active because one of their example is shown by increased frequency of pellet excretion.
The behaviour patterns to make up contact grouping in the above mentioned three periods are classified orderly into next 7 types, 1) approaching with head movement to the other worm's head, 2) approaching with head movement to the other worm's caudal leg, 3) approaching with head movement to the other worm's body side, 4) putting the body crossing on the other worm, 5) contacting each other in parallel form with same direction, 6) contacting each other in reverse direction, 7) contacting with caudal part of each individual. The types of 1, 2 and 3, appear almost in the primary period, 4 in middle, 5, 6 and 7, in the end period.
Appearance of the behaviour pattern of fasting worms are almost same as normal one, but the time of succession from one type to the other is not longer than in the case of the former. At first the worm usually contact very rapidly and if they separate, they repeat the same manner to contact again as to make aggregation. The fasted individual is attracted by the normally fed worms evidently.
The author assumes that the aggregative behaviour of the silk-worm appears prominently when they go to feeding of the mulberry leaves and enter to resting condition. It is well known that the silk-worm is one of the most domesticated insect, so that the gregarious behaviour must be a special character which has been kept through long domestication.
