TEST QUESTIONS FOR STUDENTS 927 



evolution of the race. Ontogeny tends to recapitulate phylogeny. 

 Give some clear examples. [The development of a tadpole passes 

 through piscine stages. A flat-fish, such as a plaice, is at first sym- 

 metrical, hke an ordinary Teleostean. A young Ascidian shows 

 primitive chordate characters. The kidney of even the higher Verte- 

 brates arises from the condensation and transformation of a linear 

 series of nephridia.] 



161. What are the chief uses of the blood in a Vertebrate ? [(i) To 

 distribute the digested food ; (2) to distribute oxygen from the lungs, 

 and to carry carbon-dioxide to the lungs ; (3) to collect, with the 

 help of the lymph, the nitrogenous waste-products, and bear them 

 to areas of filtration ; (4) to distribute " hormones " — the products of 

 the ductless glands or organs of internal secretion ; (5) to produce, 

 by means of certain white blood corpuscles, various anti-bodies, which 

 counteract poisons, and to carry about the amoeboid phagocytes which 

 have various useful functions.] 



162. An apparently novel structure is often an old-established 

 structure transformed and turned to a new use. Give examples of 

 this method of evolution. [The Eustachian tube is a transformed 

 gill-cleft ; the allantois of Reptiles, Birds, and Mammals is homologous 

 with the frog's cloacal bladder ; the skeletal supports of the larynx are, 

 in part at least, equivalent to gill arches ; the ear-ossicles of mammals — 

 malleus, incus, and stapes — are probably the equivalents of articular, 

 quadrate, and columella in reptiles.] 



163. Mention, with examples, the chief forms of vertebrge, classified 

 according to the curvature of the surfaces of the centra. [Amphicoslous, 

 in most fishes ; Procoelous, in most reptiles ; Opisthocoelous, in bony 

 pike, salamander, horse's neck ; Heterocoelous, in birds only ; flat 

 or gently rounded (Amphiplatyan), characteristic of Mammals.] 



164. Define secretion and excretion, giving examples. [Secretion 

 is the process by which gland-cells make as the result of metabolism 

 a non-hving product, usually organic. Thus cells in the stomach will 

 secrete pepsin and pancreatic cells secrete other digestive ferments. 

 The word is sometimes applied to the result of the process. The term 

 excretion should be restricted to the processes of filtering out nitro- 

 genous waste-products. Thus the mammalian kidney excretes urea.] 



165. Explain the terms homologous, analogous, and convergent (or 

 homoplastic) and give examples. [Homologous structures have the 

 same fundamental structure and mode of development ; e.g. wing of 

 bird and arm of man. Analogous structures have the same use ; e.g. 

 wing of bird and wing of butterfly. But homologous structures might 

 also be analogous ; e.g. wing of bird and wing of bat. Convergence is a 

 superficial resemblance of unrelated animals, due to their being similarly 

 adapted to similar conditions of life, e.g. the earthworm-Uke shape of 

 burrowing amphibian, lizard, and snake.] 



166. Give examples of the different kinds of coloration in the animal 

 kingdom. [Kinds . — (a) Physical or structural, (b) pigmentary, (c) a 

 combination of the two.] 



167. Explain what is meant by vestigial structures. Give examples 

 of ancient structures which have been reduced in size, but turned to 

 a new use. [Vestigial structures are dwindled, practically useless 



