MORPHOLOGY OF SPERM ATOPHYTES 





regarded the two ovules as representing a single flower. In 

 1890 Celakovsky 8 published the view that the stalk is an axil- 

 lary shoot bearing two or more carpels, but that each carpel is 

 represented only by an ovule. This means that the presence of 

 the carpel is purely theoretical. The same author 14 in 1900 

 reaffirms this position with greater fullness of detail. In 1896 

 Fujii, 12 after a study of abundant Japanese material, and espe- 

 cially taking into account numerous abnormal developments, 

 came to the conclusion that the stalk is a shoot, usually bearing 



two rudimentary carpels. That 

 the ovules are really related 

 to carpels appears from the 

 fact that he found them upon 

 more or less modified foliage 

 leaves. In other cases he 

 found transition stages be- 

 tween the normal collar and 

 blades bearing ovules, his con- 

 clusion being that the collar 

 represents the rudimentary 

 carpel. The short stalk which 

 is sometimes quite evident in 

 connection with each ovule 

 stands, therefore, for the peti- 

 ole of a megasporophyll. That 

 the main stalk is a shoot was 

 further evidenced by the fact 

 that cases were found in which 

 a stalk bore several ovules and 

 terminated in a scaly bud. The 

 results of Seward and Gowan's 16 studies coincide with the views 

 of Fujii. These observers have still further strengthened the 

 position by the record of additional abnormalities. 



A summary of what seems to be the most reasonable view of 

 I the homologies of the ovulate structures in Ginkgo is as follows : 

 j The main stalk represents a shoot bearing two or more carpels, 

 ] and these carpels mostly occur in rudimentary form, the petiole 

 I being represented by the short stalk upon which each ovule 

 Stands, and the blade by the so-called collar. 



The development of the megasporangium seems to be al- 



FIG. 31. Ginkgo Mloba, longitudinal sec- 

 tion of ovule : i, integument ; m, mi- 

 cropyle; p, beaked apex of nucellus, 

 with pollen chamber containing pollen 

 grains; <?, embryo sac containing an 

 early stage of the gametophyte ; c, the 

 "collar"; x 5. 



