THE CARPEL AND OVULES 119 



methylated spirit), and the sections should be treated with half 

 glycerine, half alcohol : this should be left exposed to the air in 

 a watch-glass, so that the alcohol may evaporate : mount in 

 pure glycerine. Anhydrous staining reagents may be employed, 

 but are not actually necessary. 



CARPEL AND OVULES. 



IV. The following preparations must be made from materials 

 hardened in absolute alcohol, or methylated spirit. From an 

 open bud of Caltha palustris which has been thus treated, strip 

 off the outer organs, and cut a large number of transverse 

 sections of the carpels : by so doing the ovules will be tra- 

 versed in a longitudinal direction. Treat the sections with 

 one-half pure glycerine, one-half alcohol, in a watch-glass, and 

 let the alcohol evaporate gradually : pick out those sections 

 which appear to have fairly traversed one or more of the 

 ovules, and mount them in pure glycerine. Strasburger 

 recommends that in the preparation of such objects the 

 transfer to pure glycerine should be made before the sections 

 are cut. 



Examine first with a low power, and observe 



1. The carpel, having a structure not unlike that of an ordinary 

 leaf, and consisting of an upper and lower epidermis with some 

 four layers of mesophyll between them. Note the suture or 

 junction of the two margins of the carpel, which thus encloses 

 a central cavity. 



2. The ovules (macrosporangia) seated in this cavity, and 

 attached near the margins of the carpel : it has already been 

 noted that there are two rather irregular rows of ovules in each 

 carpel, therefore at most only two ovules appear in each 

 section. 



The form of the ovule is anatropous : it consists of the 

 following parts : 



a. The funicuius, or stalk, which adheres through the greater 

 part of its course (as the raphe) to the body of the inverted 

 ovule. A procambium bundle, connected with a bundle at the 

 margin of the carpel, traverses it longitudinally. 



