106 MR. MIERS ON SEVERAL INSTANCES OF ANOMALOUS DEVELOPMENT 



the nascent eml)ryo. We will not here touch upon the still disputed point, whether the 

 process of fertilization is the result of mere imjiact, or whether the boyavi enters into the 

 primary utricle ; but will pass on to the fact admitted by all, that a new globular deve- 

 lopment subsequent to this action (the futm-e embryo) is generated within the primary 

 utricle, which is suspended within the sac by a delicate tlu-ead, often extending with 

 the growth of the embryo in its young state : this is called the suspensor, which in some 

 few instances becomes liighly developed, though more frequently it is of no great length, 

 sometimes remaining as a short distinct thread that terminates the extremity of the 

 radicle, and which I have pointed out as existing in the embryo of Stemomirus. After 

 the fecundation of the embryo, in the maimer just mentioned, the embiyo-sac as before 

 stated, either by absorption, or by amalgamation with the surrounding tissues, generally 

 disappears ; but in some few cases, as we have seen, it remains persistent, and Stemonurus 

 affords an instance of this occm-rence. 



I have entered into these details upon the nature and function of the embryo-sac, witli 

 the view of considering, Avhether a different amount of circumversion of this sac, respect- 

 ively to that of the tunics of the ovule, may not have taken place in Stemonurus, which 

 would thus account for the phaenomena under consideration. May we not conclude, with 

 some degree of confidence, that the embryo-sac has remained to form a cavity in the 

 albumen, Avhich has been copiously moulded around it, by amylaceous granules flowing 

 from the redundant amniotic fluid deposited among the cellular tissue of the surrounding 

 envelope ? Has the embryo-sac in this case moved a half-revolution on its centre more 

 than the coats of the ovule, or vice versa? I cannot ventui'e to aifirm the fact, but 

 the evidence is certainly presumptively in favour of such a conclusion. This indeed 

 appears to me the only key to the solution of the paradoxical difficulty in question. It 

 is, hoAvever, a point that can only be settled by observation on the growth and develop- 

 ment of the ovule of Stemonurus, and as it involves a topic of great importance in a phy- 

 siological and structural point of view, I would earnestly impress it on the attention of 

 every botanist who has an opportunity of examining the ovule in a living state. In the 

 mean time I call attention to the following evidence, which appears to favour this view of 

 the question. 



Cltrosma* will be found to offer some points of analogy with Stemonurus, as far as 

 regards the cyclotropal form of the raphe and its termination close to the extremity of the 

 radicle, or in other words, its anomotropal embryo. Boldoa, Sedycarya, and Mollinedia\ 

 severally have anatropous seeds, and those of Ambora and Monimia are described as 

 having a similar development, so that Citrosma appears to be the only genus in this 

 family where the raphe is cyclotropal and the embryo anomotropal. Here the raphe 

 makes nearly an entii-e gyration roimd the periphery of the seed : it originates at the 



* I take this opportunity of observing that the genus Siparuna of Aublet appears to differ in no respect from 

 Citrosma : the form of its anthers and their mode of dehiscence were supposed to offer generic distinctions, but I 

 found those of Citrosma quite agree with the description of Aublet ; in habit and floral characters the one accords 

 perfectly with the other. 



t I may also affirm without hesitation that the genus Tetratome of Poppig is identical with Mollinedia of the ' Flora 

 Peruviana.' I have examined several species and made drawings and analyses of the living plants. I purpose at some 

 future time to give the full characters of Mollinedia, Citrosma, and Boldoa, for which I possess ample materials. 



