CHAP. II. OVULE. 179 



When the ovules are attached to the placenta by a kmd of 

 cord, that cord is called \\\e funiculus (Plate V. fig. 26. a), and 

 is a mere prolongation of the placenta. 



In the beginning the ovule is a pulpy excrescence (Plate 

 V. fig. 16.), appearing to be perfectly homogeneous, with no 

 trace of perforation or of envelopes. But, as it advances in 

 growth, it is gradually (Plate V. fig. 17 to 21.) enclosed in 

 two sacs or integuments, which are open only at their apex, 

 where, in both these sacs, a passage exists, called xhefvramen 

 (Plate V. fig. 21. a); or, in the language of Mirbel, exostame 

 (fig. 25. a), in the outer integument, and endostome (fig. 

 25. Z>), in the inner integument. The central part is a 

 fleshy, pointed, pulpy mass, called the nucleus, or nucelle 

 (Plate V. fig. 19, 20. a, 22. b, 23. c, 24. d, 25. e, 27. e). 



The outermost of the sacs (Plate V. fig. 22. c, 23. a, 25. c) 

 is called the primine. It is either merely a cellular coating, 

 or it is traversed by numerous veins or bundles of tubes, 

 these are sometimes very apparent, as in the Orange tribes , 

 and Mirbel seems disposed to think that they often exist in a 

 rudimentary state when they are not visible. Usually it is 

 nearly as long as the secundine, but sometimes it is remark- 

 ably shorter, as in the Euphorbia Lathyris when very young 

 (Plate V. fig. 22.). 



The outermost but one of the sacs (Plate V. fig. 23. J, 

 20. hf 25. d) is called the secundine ; it immediately reposes 

 upon the primine, and often contracts an adhesion with it, 

 so that the two integuments become confounded. In order to 

 ascertain its existence, it is, therefore, often necessary to 

 examine the ovule at a very early period of its growth. It 

 is probable that it always exists ; but Myrica, Alnus, Corylus, 

 Quercus, and Juglans have been named by Mirbel as plants 

 in which the secundine is not perceptible (Plate V. fig. 24.). 

 Its point is usually pi'otruded beyond the foramen of the 

 primine. 



The nucleus (Plate V. fig. 22. h, 18, 19, 20. a, 24. d, 25. e) 

 is a pulpy conical mass, enclosed by the primine and secun- 

 dine, and often covered by them; but frequently protruded 

 beyond the latter, and afterwards, at a subsequent period of 

 its growth, again covered by them. Sometimes its cuticle 



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