212 EMEU 
twentieth day the beak, furnished with the hard “egg-tooth,” is 
thrust through the inner shell membrane, and the bird begins to 
breath the air contained in the chamber. Thereupon the pulmonary 
circulation becomes functionally active and blood ceases to flow 
through the umbilical vessels from and to the allantois. The latter 
shrivels up, the navel becomes completely closed, and the chick by 
repeated filing motions pierces the shell at the broad end of the egg 
with its egg-tooth. A small crack in the shell is sufficient to destroy 
the surprising strength of the intact egg, the chick casts off the 
dried, now no longer useful, remains of allantois and amnion, and 
steps out into the world. 
The length of the period of incubation seems to depend upon, first, 
the state of perfection in which the young bird leaves the egg, the 
Nidifugee requiring a much longer time than the Nidicole ; secondly, 
the size of the bird,—large birds requiring more days than small 
birds; thirdly, climate and season, because an occasional slight 
cooling of the eggs retards the development of the embryo. The 
amount of cooling will naturally be greater in cold than in hot 
climates, while the temperature of the sitting bird varies within 
small limits only. However, there seem to be no observations 
made on the question if there is a difference in the length of in- 
cubation between polar and tropical individuals of the same 
species. Experience with artificial incubators has shewn that 
during the earliest days of incubation the growth of the embryo 
can be much retarded or even be stopped temporarily by a tempera- 
ture below the normal point; on the other hand, a higher than 
normal temperature does not shorten the time of incubation but is 
rather detrimental to the embryo’s life (cf W. Evans, Jdis, 1891, pp. 
52-93). 
EMEU, evidently from the Portuguese Hma,! a name which has 
in turn been applied to each of the earlier-known forms of Ratite 
Birds, but has in all likelihood finally settled upon that which 
inhabits Australia, though, until less than a century ago, it 
was given by most authors to the bird now commonly called 
CASSOWARY. 
1 By Moraes (1796) and Sousa (1830) the word is said to be from the Arabic 
Nadma or Naéma, an Ostrich (Struthio camelus) ; but no additional evidence in 
support of the assertion is given by Dozy in 1869 (Glossatre des mots espagnols et 
portugais dérivés de Varabe. Ed. 2, p. 260). According to Gesner in 1555 (lib. 
iii. p. 709), it was the Portuguese name of the Crane, Grus communis, and had 
been transferred with the qualifying addition of ‘‘di Get” (i.e. Ground-Crane) 
to the Ostrich. This statement is confirmed by Aldrovandus (lib. ix. cap. 2). 
Subsequently, but in what order can scarcely now be determined, the name was 
naturally enough used for the Ostrich-like birds inhabiting the lands discovered 
by the Portuguese, both in the Old and in the New World. The last of these 
are now known as Rheas, and the preceding as Cassowaries. 
