Some Aspects of Tracheal Ventilation in The
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SOME ASPECTS OF TRACHEAL VENTILATION IN THE COCKROACH, BYRSOTRIA FUMIGATA (GUERIN) DISSERTATION Presented in Partial Fulfillment of the Requirements for the Degree Doctor of Philosophy in the Graduate School of The Ohio State University By THEODORE BLOW MYERS, B.Sc., M.Sc. The Ohio State University 1958 Approved by: /L Adviser Department of Zoology and Entomology ACKNOWLEDGMENT In the preparation of this dissertation the author has been under obligation to a number of persons. It is a pleasure to be able to acknowledge some of these debts. Special thanks go to Dr. Prank W. Fisk, upon whose direction the problem was undertaken and under whose direction the work was carried out. His friendly/ counsel and sincere interest are deeply appreciated. The writer also wishes to thank Dr. Robert M. Geist:, head of the Biology Department of Capital University, who provided encouragement, facilities, and time for the research that has been undertaken. ii CONTENTS Chapter Page I. INTRODUCTION............................. 1 II. M E T H O D ............ 12 The Experimental A n i m a l .............. 12 Dissection............................ 13 The Insect Spirograph,................ 15 III. THE NERVOUS SYSTEM ...................... 21 IV. TRACHEAL VENTILATION ...................... 27 'V. VENTILATION. EXPERIMENTS ................... 44 Decerebrate Ventilation.............. 44 Decapitate Ventilation............... 49 Thoracic and Abdominal Exposure to C02 • • 54 Exposure of the Head to C02 ...... 60 Ventilation in the Isolated Abdomen .... 62 Ventilation Without Thoracic Ganglia .... 65 Ventilation Without Abdominal Ganglia ... 69 Ventilation and Nerve Cord S e c ti on.... 72 VI. CONCLUSIONS ................................ 75 LITERATURE CITED.................................. 80 AUTOBIOGRAPHY.................................... 84 iii LIST OF ILLUSTRATIONS Figure Page 1. The Insect Spirograph 16 2. The Immobilization Cage 18 3. The Ventilation Chamber 19 4. Byrsotria: Central Nervous System 22 5. Byrsotria: Dorsal View 23 6. Byrsotria: Ventral View 24 7. Spirogram; Normal 28 8. Spirogram; Normal With COg 29 9. Composite Graph of Normal Spirograms 31 10. Enlarged Ventilatory Movement 33 11. Frames of Motion Picture Showing Ventilation 34 12. Spirogram; Horizontal and Vertical Movement 36 13. Spitogram; Movements of Recovery 37 14. Ventilation of Smoke 42 15. Spirogram; Decerebrated Roach 46 16. Spirogram; De c er ebrat ed Roach with.COg 47 17. Spirogram.; Escape From Regulation 48 18. Spirogram; Decapitated Roach 50 19. Spirogram; Decapitated Roach With COg 53 20. The Separation Chamber 55 iv Figure page 21 . Spirogram; Three Body Regions 56 22. Spirogram; Isolated Abdomen 63 23. Spirogram; Removal of Tliird Thoracic; Ganglion 66 24. Spirogram; Comparison of Thoracic Ganglia 68 25. Spirogram; Excision of Abdominal Ganglia 70 2 6 . Spirogram; Excision of Abdominal Ganglia 71 27. Spirogram; Nerve Cord Section; 73 V I. INTRODUCTION The insect, like man, must breathe. Many persons have been struck by the seeming similarity of the rhythmic; pumping of the thorax of man and the abdomen of the insect. The idea of similarity is short-lived, however, since further thought shows that only a very few of the actual mechanisms of the insect are homologous to the various respiratory processes of man. This tracheal arrangement, even though far different from the ventilatory design of the mammal, is a highly successful and versatile plan. The animals having this tubular method of supplying oxygen to their tissues have adapted to many environments and have become man's chief competitor. The motivation for this research came during a laboratory period in insect physiology in which each student was asked to prove, in his own manner, that an active insect carries on respiration at a greater rate than does a quiet insect. Ordinary observation of the animal during periods of mechanical ventilation proved to be insufficient in determining reactions, especially during periods of rapid or shallow breathing. Kymographic recording of the pulsations seemed the logical solution to the problem, and further experimentation led to the development of the insect spirograph. t 2 It was found that at least three other investigators had utilized this approach. Regan (1911) devised a method for the graphic recording of "breathing movements in which the insect (grasshopper) was held at the small end of a conical tube. A rod extended from the ventral abdominal region of the insect to a lever arm which recorded the movements on a revolving drum. The drawback of this method was the unnatural positdm of the insect and the fact that test gases were not able to circulate freely about the Insect. Babak (1912), in work with Dytlscus. used the kymographic method of recording ventilation by pinning the insect and cutting a hole in the elytra in order to hook the animal to the lever arm. The difficulty with this approach, according to Van der Heyde (1922), was the fact that the whole Respiratory apparatus of Dytisous is covered by the large elytra; Babak1s findings do not, therefore, represent the normal breathing cycle of the beetle. Schreuder and Be Wilde (1951) suspended insects in an open glass tube by fixing them in a rubber membrane fastened at one end of the tube. A small clamp connected the last abdominal terglte with a writing lever of straw. The vertical position of the body and the clamping of the neck of the insect in the rubber membrane could scarcely be termed normal. The recording of telescoping movements rather than the deeper dorso-ventral contractions also gave spirograms very weak in amplitude* Much of the data on the rate of tracheal ventilation found in the literature are "based only upon observation by the naked eye. Herber and Slifer (1928), for example, placed grasshoppers in paper cones having observation holes cut so that the abdominal movements could be counted. Other -writers have devised original methods of counting and recording the rate of external respiration. Van der Heyde (1922) perfected an apparatus in which Dvtlscus ventilated into a closed space leading to a capillary tube containing a droplet of petroleum. Movement of the drop gave an indication of respiratory action. McGovran (1931) and Kitchel and Hoskins (1935) clamped insects in a partition between water manometers in order to measure the output of tracheal ventilation. Punt (1949) was able to measure individual outbursts of carbon dioxide by means of a diaferometer. This instrument traced carbon dioxide- influenced readings upon photographic paper and thus indirectly recorded ventilatory movements. Roeder (1951) cemented glass styli into the tergum of insects in order to measure thoracic contractions during flight. The stylus was placed in the needle holder of a crystal phonograph pick-up which was connected to the input of a conventional biological amplifier. The motions were then recorded on a double beam cathode ray oscillograph. Many Insects effect a varying degree of mechanical ventilation of the larger tracheal trunks. It has been pointed out "by Babak (1912) and others that the muscular movement of the insect body as well as the contractions of the heart and intestines assist this ventilation. Demoll (1927) has shown that flight movements of mosquitoes and walking movements of other insects greatly assist their ventilation. Roeder (1951) and Fraenkel (1932) have also made important advancements in this respect. In many of the larger- insects specialized movements of the body wall occur which serve to ventilate the respiratory tract. Plateau (1884) gives detailed accounts of these movements as does Babak (1912). As a rule these contractions are: confined to the abdomen, although some insects may also utilize thoracic.: contractions; Blatta orlentalls is one of the latter according to Imms (1925). Ventilatory movements are usally active in only the expiratory phase, although Lee (1925) reports that the grasshopper possesses Inspiratory muscles. Snodgrass (1935) presents detailed drawings of the musculature of ventilation. Some early workers believed that the pressure of expiration drove gases into the finer tracheoles when the spiracles were closed; Demoll (1927) could obtain no evidence for this, nor could Krogh (1920) in working with the closed tracheal system of Aeaohna naiads. Reference is still made to the "compressatory phase” of respiration, since McCutcheon (1940) and: others feel that, whatever its function, it is a part of the normal cycle of respiration. The most credited concept of mechanical ventilation is that which states that alternation of body movements dilate and compress the larger tracheal vessels, bringing about a ventilation of this system Just as do the movements of diaphragm and Intercostal muscles of the: mammals, except in a reverse pattern; the mammalian pattern of eupneic:expiration is passive, while in the Insecta the passive phase is generally inspiratory. The explanation of ventilation through the tracheal tubes was made more plausible after it was discovered that modifications of the trachea were present in many of the animals exhibiting forced ventilation. Dtmavan (1929) has shown that in the larva of Erlstalls the enlarged tracheal trunks not only flatten during expiration but become shorter, the taenldla coiling up like a Bpring. Krogh (1920) showed the main trunks of Dytiscus to be elliptical in cross section, and in other insects large air sacs are known to be present. These air sacs probably serve to increase the volume of tidal air (Lee, 1929), much as do the non-vasoular air sacs of the Aves. An indication of the efficiency of the tracheal ventilation is given by Krogh (1920), who found the total capacity of the respiratory system of Dytiscus to be 107 cu.mm., and its vital capacity to be 64 ou.mm. This would indicate that during hyperpnea two-thirds of the tracheal system could be emptied in one expiration. The question has often been raised about whether a directed stream of air can be driven through the tracheal tract of the Insect. Lee (1925, 1927a), in underwater testing with the Orthoptera, came to the conclusion that the thoracic spiracles are mainly inspiratory and the abdominal spiracles expiratory.