392 MORPHOLOGY OF OVULES. [BOOK i. 



errors and omissions which have since been corrected by the 

 elaborate researches of Fritzsche, Schleiden, Griffith, Brown, 

 and others. 



Ovules have been compared to buds, and have been shown 

 to be analogous to them in structure. This theory seems 

 to be established by such plants as Bryophyllum, which 

 habitually form buds on the margins of the leaves; or of 

 Malaxis paludosa, in which the edge of the leaf is frosted by 

 little microscopical points, that are neither exactly ovules 

 nor exactly buds ; or even by the bracts of Marcgraavia, 

 which Turpin, with much ingenuity, has endeavoured by 

 mere argumentation to prove analogous to the primine of 

 the ovule. It has been shown by Henslow that in the 

 Mignionette the ovules do actually become transformed into 

 leaves, either solitary or rolled together round an axis, of 

 which the nucleus is the termination. (Cambr. Phil. Trans. 

 vol. v. part i.) Engelman, also, mentions and figures instances 

 of similar changes ; but he does not say in what plants, nor 

 are his figures satisfactory. He, however, concludes, from 

 the observations of himself and Schimper, that " the ovules 

 are buds of a higher order, their integuments leaves, and 

 their stalk the axis ; all which, in cases of retrograde meta- 

 morphosis, are converted into stem and green leaves ." (De 

 Antholysi Prodromus, 44. 76. t. 5. f. 4, 5.) One would 

 rather say that the evidence goes to prove the ovule to 

 be a leaf-bud in a particular state, the integuments to be 

 scales (i. e. rudimentary leaves) rolled up and united at their 

 touching margins, and the nucleus to be the growing point, 

 to which I have already on so many different occasions directed 

 attention. 



The correctness of this view has been maintained by 

 Dr. Giraud who regards it as being "established on the 

 following grounds. The primine and secundine, at a very 

 early period of their development, are not presented each as 

 a continuous membrane encircling the nucleus, but they 

 consist of several portions, forming two whorls of what I 

 would term ovular leaves, their internode being wanting ; its 

 normal position being occupied by a portion of tissue near 



