The influences of gases and temperature on the cardiac and respiratory movements in the grasshopper

✍ Scribed by Walling, Eulalia V.

• Publisher: John Wiley and Sons
• Year: 1906
• Tongue: English
• Weight: 491 KB
• Volume: 3
• Category: Article
• ISSN: 0022-104X
• DOI: 10.1002/jez.1400030409

✦ Synopsis

T h e object of the experiments recorded in the following pages was to ascertain the influences of certain gases upon the cardiac and respiratory movements of the grasshopper, both in the uninjured animal and when the heart and respiratory centers were isolated from all or part of the body.

T h e principal parts of the respiratory organs are the paired spiracles, with their air sacs, and the tracheal tubes, that ramify from these to all parts of the body. T h e mechanical respiratory movements consist of an expiratory and an inspiratory phase. During the latter, the active contraction of the abdominal muscles increases the breathing space by enlarging the antero-posterior and dorso-ventral diameters of the abdomen. I n consequence of the lowered pressure therein produced, air passes into the tracheal tubes. During expiration the muscles relax and air enters the air sacs.

T h e heart extends as a delicate tube longitudinally above the intestine, directly beneath the chitin, along the whole length of the abdomen. When entirely exposed to view it is seen to pulsate rhythmically throughout its whole extent. By a system of valves it is divided into a series of eight chambers, that communicate through slits or ostia with a surrounding pericardial sinus. Through the aorta, which arises at the anterior end of the heart, and the aortic branches, blood is conveyed to all parts of the body, along the paths of the tracheal tubes.

It was demonstrated by Ewingl that the respiratory movements persist not only in decapitated animals but also in the isolated abdominal segments, in which are contained the ganglia of the ven-Ewing, H. Z.