02 OVULE. 



two sacs. The outer one c. is caWed primine, the inner one d. the 

 Secimdine. These sacs a;e very much open in the early- 

 statue of the ovule, and in fact in some plants are not unlike 

 two tea cups one within the other, with the nucleus in the 

 yxr /^-v inner cup as seen in fig. 115, where « is the 



primine, h the secundine, and c the nucleus. 

 These sacs increase in size and contract th<^»r 

 orifice, till the secundine closes over the nu- 

 cleus entirely, with the exception of a very 

 small orifice, called -a. foramen, fig. 114, b, 

 and the foramen of the secundine is cailed by 

 Mirbel endostome. The primine in its growth encloses the 

 secundine and nucleus, with the exception of a foramen cor- 

 responding to that of the secundine and called the €xosto?ne» 

 These terms are not in general ue, and it is doubted whether 

 the importance of the distinction demands their application. 

 It is true that in some cases the foramen of the secundine does 

 not exactly correspond to that of the primine. The simple 

 term foramen however, answers all practical purposes. There 

 are three other coverings of the nucleus described by some 

 Botanists named terchie, quartine and quintine, but much un- 

 certainty exists in reference to them, and great difference 

 in opinion, even among the most distinguished philosophers, 

 some even denying their existence. We deem it inexpe- 

 dient to occupy our space with the discussion of a subject 

 concerning which, from our own observation, we have been 

 unable to come to any satisfactory conclusion. The figure 

 to which our illustiation is applied, the student will perceive, 

 exhibits the nucleus and its coverings m a curved position ; 

 this is its true position in a perfect state in many plants, but 

 not in its early stage ; in the progress of development, it 

 assumes this position. The ovules of different plants, although 

 the relative position of the parts are nearly the same in their 

 early stage, yet in their growth, assume several different 

 positions reducible to four different types. 



108- When no change of position takes place, but the base of 

 the ovule remains next to the placenta with the axis straight 

 and the foramen at its extremity, it is said to be Orthotropus 

 ITG /\ ^^ *" ^o* ^^^^ which is the case in the nettle. But 

 \ it frequently happens that one side of the ovule 

 \ only is developed and the axis becomes 117/ — 

 I doubled on itself, so that the foramen is 

 ^ J contiguous to the base or hilum, as in 

 f fig. 117, which is called Campylotrojms. 

 In other cases the whole ovule becomes inverted 

 so that the foramen points towards the placenta 



