THE ORCHID EMBRYO SAC 1 



Lester W. Sharp 



(with plates xxi-xxiii) 



During the spring of 1910 it was the writer's privilege to visit 

 island of Jamaica as one of a party of botanists from the Johns 



j 



1 



son. In view of the number 



embry 



j 



Baltimore, mi 



several reasons prove of value. 



& 



evolutionary 



extreme 



features, may be expected to show instructive deviations from the 

 usual type of embryo sac, and it is through a study of such 

 deviations that a final explanation of the origin and nature of the 

 angiosperm embryo sac will probably be reached. They should also 

 be most likely to reveal the end result in the reduction of the female 

 gametophyte, which is seen occurring as one passes from the lower 

 heterosporous groups to the higher. Furthermore, the data at 

 hand on the orchid embryo sac, in part very suggestive, have been 

 somewhat scattered, the details being well known in comparatively 

 few forms, so that we have not known just what relation the cases 

 reported bear to any general situation which may be present among 

 orchids. 



Although the number of additional species here described is 

 small for a group as large as the Orchidaceae, they are well scattere 

 throughout the family, so that taken together with species pre- 

 viously described they place us in a better position to draw con- 

 clusions on the general tendency of the group. 



For the sake of clearness the different forms will be considere 

 separately, and only two or three of them in detail. 



1 Botanical contribution from the Johns Hopkins University. No. 25. 



Botanical Gazette. voL <a] ' ' 3/ * 



