^j4 Comparative Animal Physiology 



increases the effect of adrenalin, has no effect on the action of histamine, 

 and abolishes the action of tyramine. Nervous stimulation augments stomach 

 movement, an effect abolished by cocaine, and when the entire animal is 

 perfused, stimulation of visceral, branchial, and other nerves causes the ap- 

 pearance in the perfusate of something resembling tyramine.-" Neuromus- 

 cular transmission in cephalopods merits further investigation. 



There is inconclusive evidence for cholinergic systems in flatworms (Ne- 

 merteans and Platyhelminthes); the concentration of ChE in mixed muscle, 

 nerve, and other tissue is strikingly high (Table 73). Strips of Cerehratiilus 

 muscle are unresponsive to ACh alone, but after eserine they respond to ACh 



5 X lO-^^^'' 



Evidence points against cholinergic systems in ascidians, crustaceans, and 

 coelenterates. Extraction of the ascidians Ciena and Phallusia failed to show 

 measurable ACh and showed httle ChE (Table 73). The mantle muscle of 

 Cynthia is stimulated by ACh but the response is not potentiated by ese- 

 rine. ^^ 



In Crustacea the nerves, particularly in the central nervous system, are 

 rich in ACh. Muscles in Crustacea have no ACh but do contain some ChE 

 (Table 73). Crustacean muscle is insensitive to ACh, eserine, and curare.^*'- 

 89. 138, 93 Careful testing of the effects of many drugs and ions on neuro- 

 muscular transmission failed to provide any evidence in Crustacea for humo- 

 ral transmission. Tyramine is without effect,^"*^ although adrenaUn in high 

 concentration causes contraction. ^^^ Crustacean claws should be well adapted 

 for identifying exciting and inhibiting mediators, but no one has yet suc- 

 ceeded in such identification. Insect muscles are insensitive to acetylchoHne, 

 even after soaking in anticholinesterases. 



Among coelenterates ChE was found in Tiihularia, Metridium, and Sa- 

 gartia but not in any regions of the medusae Cyanea and Aurelia, and not 

 in the ctenophore Mnemiopsis.^'^ Muscles of the actinians Calliactis and 

 Metridium were insensitive to ACh, even after eserinization; also no effect 

 was observed with eserine, atropine, curare, and adrenalin. ^^^' ^°^ Contrac- 

 tions of medusae were also unaffected by ACh or eserine. ^^ In Calliactis, 

 however, tyramine enhances facilitation by 3-4 times in 84-90 minutes and 

 can even permit a response to single shocks. Extracts of this anemone yield 

 a substance, perhaps tyramine, which promotes facilitation.-^'^ Cholines- 

 terase and ACh are lacking in sponges. 



Table 73 mdicates that cholinergic neuromuscular systems function in ver- 

 tebrates, annelids, and echinoderms, are suggested in molluscs and flatworms, 

 and are contraindicated in ascidians, arthropods, and coelenterates. Adrener- 

 gic systems have been demonstrated only in vertebrr.ces, and tyraminic sys- 

 tems have been suggested for c phalopods and coe'.interates. 



DISTRIBUTION OF PHOSPHAGENS 



The energy relations and the biochemistry of muscles other than of ver- 

 tebrate striated muscles are poorly known. The heat liberation by vertebrate 

 striated muscle has been carefully studied and analyzed as heats of contrac- 

 tion, relaxation, and recovery. Except for crustacean muscle, no useful ther- 

 mal data are available for other muscles. 



