CHALAZOGAMAE 
308 
never emerging from them , to the stalk of the ovule, which it thus 
enters from the chalazal end. It passes upwards inside a sterile 
macrospore and finally enters the fertile one and fertilises the ovum. 
The endosperm is formed by the free nuclei in the embryo-sac, in 
the usual maimer. 
Both in the development of the macrospores and in the process of 
fertilisation, the difference between Casuarina and all other known 
Angiosperms (except to some degree the Loranthaceae) was so 
marked, and seemed to place Casuarina so much nearer to the 
Gymnospermae (q.v.), that Treub proposed to rearrange the Angio- 
sperms thus : 
r rorogamae 
Angiospermae ■ 
Chalazogamae 
This proposition has not met with general acceptance. The phe- 
nomenon has since been observed in various plants of the allied 
orders Betulaceae, &c. In Carpinus Betulus there are several 
embryo-sacs with tubes (caeca) running down into the chalaza, and 
the pollen tube enters the base of one of these and passes up to the 
ovum, which is of the ordinary type with synergidae, &c. In Corylus 
Avellana there are several embryo-sacs, but only one sends down a 
caecum. In Alnus glutinosa there is one embryo-sac deep in the 
nucellus, with no caecum, and Betula alba is somewhat similar. 
Some of the Fagaceae also show signs of this peculiar embryo -sac 
development but are fertilised by way of the micropyle. In Corylus 
and in Juglans regia the embryo-sac at the time of fertilisation 
contains the 3 antipodal cells and 5 free nuclei, with one of which 
the male nucleus coalesces, so that a relationship to Gnetum (see art. 
Gymnospermae) is perhaps indicated. Ulmus shows signs of chalazo- 
gamic fertilisation, though the pollen tube finally reaches the apex of 
the nucellus, and Plantago also is said to exhibit somewhat similar 
phenomena, while in Alchemilla sp. the tube enters by the funicle 
and afterwards runs up through the integument and enters the 
embryo-sac at the level of the ovum. 
We may perhaps accept the view that chalazogamic fertilisation 
is one of the phenomena attending the passage from gymnospermy to 
angiospermy, but to base any classification upon it would be pre- 
mature. [See Nawaschin, Bull. Ac. St. Petersb. 1899, Bot. Zeit. 1900, 
p. 38; Murbeck, Lunds Univ. Arskr. 36, Bot. Centr. 86, p. 121.] 
Chamaecyparis Spach. Coniferae (Arauc. 2 c ; see C. for genus 
characters). 4 sp. N. Am., Japan. C. nutkaensis Spach. (Thuya 
excelsa Bong.) is the Sitka cypiess or yellow cedar; C. sphaeroidea 
Spach ( Thuya sphaeroidalis Rich.) is the white cedar of N. Am. ; C. 
(Th.) pisifera Sieb. et Zucc. and C. (Th.) obtusa Sieb. et Zucc. are 
Japanese. All yield useful timber, especially the first two. The 
genus is much confused with Thuya and Cupressus (in nomenclature). 
\Dicotyledones. 
\ Monocotyledones. 
