Chap. III.] GENERAL ANA 7^0 MY. //^F 3I 



system incidentally in the last chapter. Further study we will 

 reserve for Chapter vni, 



7. The Muscular System. Of this system little can here be 

 said. Suffice it to remark that most of the muscles have their 

 origin in some bone or other part of the body which is relatively 

 fixed, and their insertion in some bone or other part of the body 

 which has to be moved. There are some muscles, however, 

 which encircle certain parts of the body, generally tubular, and 

 by their contraction serve to lessen the diameter of the tube or 

 completely close it. 



8. The Integumentary System. Nothing need here be added to 

 that which was said in the last chapter. 



In conclusion, attention may be drawn to the following points 

 for the sake of 'future comparison : 



1. The lungs are contained in the pleuro-peritoneal cavity or 

 ccelom, together with the liver, alimentary canal, generative 

 organs, spleen (7, Sp.), etc. 



2. The heart has one ventricle and two auricles; a sinus 

 venosus, and a truncus arteriosus. 



3. There are two systemic aortic arches. 



4. Blood is distributed to the kidney by renal portal veins 

 from the posterior end of the body, as well as by renal arteries 

 from the aorta. 



5. There is a large anterior abdominal vein. 



6. The kidneys lie in the large subvertebral lymph sinus. 



7. There is a common duct for the testis and the renal organ 

 in the male. 



8. The apertures of the urine-genital duct of the male, and of 

 the ureters and genital ducts in the female, are on the dorsal 

 side of the cloaca. 



9. The urinary bladder opens into the ventral side of the 

 cloaca. 



10. There is a common cloacal aperture for the exit of the 

 "faeces from the alimentary canal and for the urino-genital pro- 

 ducts. 



11. Respiration is by means of gills in the tadpole and lungs 

 in the frog. 



