42 BOTANICAL GAZETTE [jawjary 



observed 



these structures 



Marchantia polymorph 



(presuma 



gemmae) took exactly the places of archegonia. Yet cupules and 

 archegonia are not homologous. 



When against homology, the invasion may be partial 



degree. 



may 



Without entering into details, the literature of ovular abnormality 



of this opinion. 22 Even when the imitating 



imitated structures 



from 



organ may merely be indicated by some faint resemblance, or may 

 be pronounced in any degree up to the total replacement of the local 

 member by the foreign. • 



A corollary of the above propositions (5 and 6) may be stated: 

 Homology of two organs cannot be inferred on the ground alone of 

 the replacement of the one by the other, or of the translocation of 

 features proper to the one into the other of the organs. The exist- 

 ence of even a so-called "complete" series of gradations between 

 two members does not necessarily imply the homology of the mem- 

 bers. I think that the anamorphoses of Celakovsky have not the 

 extraordinary phylogenetic significance, as compared with other 

 kinds of abnormality, which this author has attributed to them. 



7. In homoeosis characters may pass from one to the other of the 

 alternating generations. 



Yamanouchi has recently published 2 * an account of the very 

 interesting conditions attending apogamy in Nephrodium molle. The 

 apogamous prothallia bear no functional archegonia, but they pro- 

 ceed to initiate the sporophyte directly. A superficial cell on or near 

 the cushion divides perpendicularly to the surface, and underlying 



cells divide in various directions. From the .„ \ 



the sporophyte develops. The cytological history" being" followed 



"Bot. Zeit. 33:747. 1875. 



» Wigand, A., Grundlegung des Pflanzen-Teratologie 39. Marburg. 1850; 

 Masters, op at. 186, 26 2 - 27l; Wyd LER , Denkschr. Regensb. Bot. Gesells. 

 4=77- 1850; Planchon, article cited; Celakovsky, Bot. Zeit. 33:1^x77. 187* 



"I Box. Gazette 44:143. I0O7; 45:2g9> ig ^ 



com 



