THE KANSAS UNIVERSITY 

 SCIENCE BULLETIN. 



VoL.V, No. 5] OCTOBER, 1909. [™xv'™l 



THE NUTRITION OF THE EMBRYO SAC AND EMBRYO 



IN CERTAIN LABIATE. 



BY F. H. BILLINGS. 

 Plates XI to XIV. 



^^OON after the publication of a paper on seed development, 

 ' in which various sympetalous families were considered, 

 Ihe writer began an investigation of embryo-sac nutrition as 

 found in the Labiatse. Literature upon the subject indicated 

 the presence of certain nutritive structures that resembled 

 some of those described in the paper mentioned above. The 

 structures consisted of outgrowths or specialized portions of 

 the embryo sac which by enlargement frequently replaced con- 

 siderable portions of the integument. The position and shape 

 of the structures are characteristic in some instances of the 

 family in which they occur. It is therefore one of the prob- 

 lems of the present investigation to ascertain what degree of 

 uniformity prevails among a number of genera of the Labiatse, 

 and thus determine, if possible, whether any special type of 

 embryonic structure is liable to become characteristic of the 

 family. Though the number of species studied is but a small 

 representation of the total number distributed over the earth, 

 still, as will presently be shown, a great enough similarity ex- 

 ists among them to warrant the supposition that a like re- 

 semblance probably exists among the remainder. It would not 

 be safe to extend such a conclusion to any family taken at 

 random, inasmuch as some families are aggregates of groups, 

 such as subfamilies, which may not be closely allied phylo- 

 genetically but which are associated on account of fulfilling 

 certain taxonomic requirements. 



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