﻿throughout was Haidenhain's iron-haematoxylin, as this gave 

 excellent differentiation in all stages. Good results in the post- 

 fertilization stages were obtained with carthamine (gossypimine) 

 and picric-aniline blue. Many other stains were tried, but none 

 of them was as good as the two already mentioned. 



Ovule and embryo sac 



The ovary usually consists of 3 carpels and is trilocular, each 

 loculus containing about 4 not very definitely anatropous ovules 

 arranged in an axile manner. These ovules have the massive basal 

 part of the outer integument so characteristic of the Araceae. 

 The inner integument closes about the time that the megaspore 

 mother cell shows signs of the first division leading to the forma- 

 tion of the embryo sac. The outer integument remains open until 

 endosperm development is well under way. 



The two integuments show numerous changes throughout their 

 course of development. The inner one does not attain any great 

 thickness, never being more than 2 or 3 cells thick. Before ferti- 

 lization, the cells of the innermost layer of this integument, espe- 

 cially those cells in the region round the lower part of the embryo 

 sac, grow rapidly in a plane at right angles to the axis of the ovule 

 (fig. 11a). After fertilization, cells of this layer again grow rapidly 

 and gradually lose their flattened form, although they still remain 

 conspicuous by reason of their large size. The chief feature of the 

 outer integument is its great thickness in the chalazal region. It 

 is composed of small uniform cells, with here and there a large cell 

 containing raphides. These large cells are in every way similar 

 to those found in the ovary wall. As the seed matures, intercellular 

 spaces appear in the integument, and the outer surface becomes 

 lobed, particularly at the micropylar end. 



The nucellus, as in most other Araceae, is not very permanent 

 tissue, and by the time the egg is ready for fertilization all that 

 remains of it is a cap above the embryo sac and a few cells at the 



The archesporial cell is differentiated early, before the origin 

 of the second integument. It is easily distinguishable by its denser 

 protoplasm and somewhat larger nucleus. Soon after the appear- 



