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ment. Since the usual terms testa and membrana interna 

 are not applicable to these envelopes, he proposes that of 

 integumentum simplex for the one case, and those of inte- 

 gumentum externum and internum where the nucleus is in- 

 closed in two envelopes. The difficulty in the investigation 

 of the ovule is chiefly caused by its being in a great number 

 of plants reflected, even long before impregnation, and this 

 reflexion occurs both in the naked ovules and in those which 

 are provided with simple or double integuments. M. Schlei- 

 den ascribes all reflexions of the seeds of plants to the axile 

 formation, and therefore to the nucleus, with which I cannot 

 agree ; he moreover only enumerates the two cases where the 

 axis remains straight (ovulum atropum), and the other where 

 the axis is reflected and produces the ovulum anatropum. In 

 a physiological respect these reflexions are very unimportant, 

 for in many "plants I have found some ovules not reflected, and 

 nevertheless perfectly impregnated; but to systematic botany 

 these reflexions of the ovule are very important, and the third 

 division which even earlier botanists have established, that of 

 the amphitropous seed, is quite indispensable. I shall en- 

 deavour to show in another place that the amphitropous seed 

 must not merely be considered as a transition-form between 

 the atropous and anatropous seeds ; and moreover the frequent 

 reversions of the ovule by a subsequent curvature of the um- 

 bilical cord must be designated by distinct terms. The forma- 

 tion of the integuments of the nucleus is very accurately 

 and minutely described by M. Schleiden, and what I have ob- 

 served on this subject fully coincides with his statements; 

 I also agree perfectly with him that MirbePs quartine does 

 not exist as a distinct membrane. 



Although it is easy in cases with true placenta centralis li- 

 bera or as in the Polygonea., in Taxus, &c. to explain the nu- 

 cleus as the mere apex of the axis, yet it might prove difficult 

 to many botanists in the case of parietal placentae : however 

 M. Schleiden enumerates several examples which give to this 

 view a high degree of probability ; for example, the ovaria of 

 the Fumariaceae and Cruciferts and the cones of the Abietince. 



These views of M. Schleiden will certainly meet with great 

 opposition : hitherto it was generally admitted that the ova- 

 rium consisted of buds which formed at the margins of leaves. 



