GINKGOALES 



195 



will serve to illustrate the progress of interpretation, and especially 

 will show the result of attempting to read the structures of a higher 

 group into those of a more primitive one. 



In 1869 \'an Tieghem (2) interpreted the stalk as a petiole; 

 the two ovules as determined by the two characteristic lobes of the 

 blade; the collar as a reduced aril; and hence the whole structure as 

 a single megasporophyll (carpel). In 1872 Strasburger (4) sug- 

 gested that the stalk is a shoot; that the collar is the rudiment of the 

 first pair of leaves of a secondary shoot; and hence that the whole 



Fig. 222. — Ginkgo biloba: dwarf shoots with ovulate strobili; the leaves have been 

 cut away from the shoot at the right; the female gametophyte in such ovules is in a 

 very early free nuclear stage; Xi .5.- — After Coulter (54). 



structure is an inflorescence of two flowers in which the carpel is 

 suppressed. In 1879 he modified (6) this view in so far as to conclude 

 that the collar represents an aril. In 1873 Eichler (5) interpreted 

 the collar as the outer integument of the ovule, which view is not 

 necessarily inconsistent with the preceding views that it stands for 

 an aril; later (10) he called the collar a rudimentary carpel. In 

 1890 Celakovsky (ii) stated that the stalk is an axillary shoot 

 bearing two or more carpels, but that each carpel is represented only 

 by an ovule, which means that the existence of the carpel is only 

 theoretical; later (25) he reaffirmed these views with greater fulness 

 of detail. In 1896 Fujii (17), after a study of abundant Japanese 



