MUSEUM OF COMPARATIVE ZOOLOGY. 115 



Summary. 



1. The first food of young gar-pikes after the absorption of the yolk 

 is mosquito larvae ; later, they feed on small fishes. 



2. Very cold water is injurious to young gars. 



3. The arched form which the body sometimes exhibits is probably 

 always the result of an abnormal condition. 



4. The acts of catching and swallowing the prey are complicated. 

 Fishes are usually swallowed head first. 



5. The young gar-pike lives at the surface of the water after the 

 absorption of the yolk-sac. 



6. The emission of bubbles of gas through the gill slits is accompanied 

 by a rolling of the body to one side and a forward movement. 



7. Analyses of the bubbles of gas emitted by young fishes, and also 

 of a limited amount of atmospheric air which had been used by the 

 fishes in respiration, showed a reduction of the oxygen to 10-15 per 

 cent, and the presence of only a small amount of carbon dioxide, 0-1.7 

 per cent. 



8. Air which had been previously deprived of its carbon dioxide gave 

 no evidence of containing even a trace of that gas, after having been 

 respired. Consult the text for the conditions of experimentation. 



9. It is probable from these experiments that the air-bladder respira- 

 tion serves to oxygenate the blood, but that the elimination of carbon 

 dioxide is effected in some other manner. It is possible that the two 

 elements of the respiratory function of higher vertebrates were succes- 

 sively transferred to -the air-bladder, that of oxygenating the blood being 

 the first to be transferred. 



10. There are two egg membranes in Lepidosteus, — a zona radiata 

 and a villous layer, — and they are intimately joined together. Both are 

 radially striate, the zona finely, the villous layer coarsely. 



11. Balfour and Parker were mistaken in stating that there was a 

 homogeneous non-striate membrane inside the striate zona, and also in 

 supposing that the pyriform bodies (villi) of the outer covering were 

 metamorphosed follicular cells. 



12. The outer layer is not as thick as the zona, and is made up of 

 radially compressed and folded columnar structures, the villi. 



