Jax. 1902.] BOTANICAL SOCIETY OF EDINBURGH 



149 



as compared with plants ; and this fact was insisted upon 

 some years ago by J. A. Murray and myself.^ 



At that time we compared the two modes of development 

 in tabular form, and we postulated the formation of the embryo 

 upon the asexual generation or larva from a spore-mother- 

 cell. Certain facts supporting this view were cited, including 

 E. B. Wilson's teloblasts of the earthworm, which must be 

 derivable from one cell. Finally, the spore-mother-cells have 

 appeared in the primary germ-cells of the present research. 



Revised Comparison of Metazoax and Metaphttic 

 Life-Cycles. 

 Metazoon. Metaphyte. 



f zygote (2n) zygote (2n) 



" larva '" or phorozoon (2n) 



I 

 formation of primitive 

 germ-cell (2n) 



1 

 formation of primary 

 germ-cells (2n) 



" apospory "' (reduction 

 postponed) 



sporophvte (2n) ■ 



I " 

 formation of primitive 

 spore-motlier-cell (2n) 



I 

 formation of spore-mother- 

 cells (2n), probable 



I determination of sex 

 I and reduction 

 spore- formation 



[ primary germ-cells (2n) 



initiation of determination of 



sex 



origin of embryo or gameto- 



zoon from one primary gerni- 



cell, inclusion of rest in 



gametozoon (2n) 



I 

 end of determination of sex, 

 and reduction of chromo- 

 somes 

 ripening of germ-cells 



spermatozoon (In) egg (In) 



zygote (2n) 



spores (In) 



origin of gametophyte from 

 one spore 



(In) 



ripening of germ-cells, reduc- 

 tion previously ell'ected 



male female 



gamete (In) gamete (In) 



zygote (2n) 



In the above table " n " e(|uals the number of chromosomes prior to 

 the duplication (" 2n ") at conjunction — that is, fertilisation. 



X.B. — Although the primary germ-cells and the spores are shown 

 in the table in the same line, they are not equivalent. The former 

 correspond to the spore-mother-cells. 



1 J. Beard and J. A. Murray : " On the Phenomena of Reproduction 

 in Animals and Plants." — " Anat. Anz.," vol. xi., pp. 234-255, and also 

 in "Ann. of Botany," vol. ix., pp. 441-468. 1895. 



