INTRODUCTION TO CRYPTOGAMIC BOTANY. 55 



be met with in a different and inferior series, but not in 

 points indicating inferiority. 



41. External resemblance is very often deceptive in tracing 

 the relations of plants to each other, and an utter difference of 

 aspect may be consistent with close affinity. Similar organ- 

 ization will sometimes exist in widely-separated plants, while 

 difference of structure will be found even in plants of tliQ 

 same genus where habit is different. The distinctive mark, 

 for instance, in coniferous wood, which was, at one time, 

 thought decisive as to affinity, is not confined to Conifers. In 

 Magnolias and Witch Hazles (Hartiamelidacem) we have the 

 same structure, whatever pains may be taken to explain it 

 away ; and if it is considered that ordinary woody tissue 

 succeeds uniformly to the glandular tissue in Conifers, as the 

 year advances, the one being actually produced from the 

 other, we need not feel surprised that it is not certainly 

 indicative of affinity. Nothing can be much closer than the 

 general appearance of the fruit in Pepperworts and Arads, 

 and if annual stems be examined there are the same scattered 

 fascicles of woody tissue. The inflorescence, indeed, of all is 

 not the same, but this would merely be exceptional were the 

 structure of the stem really identical ; but take an old pepper 

 stem and you have strong plates of medullary tissue, and may 

 count the annual rings. Hence, though, up to a certain point, 

 there is endogenous stracture (with the exception of the cha- 

 racteristic crossing of the woody bundles), you have the 

 two cotyledons to convince you that such eminent botanists as 

 Blume and Richard have been led astray by analogy, when 

 they considered them as true Endogens. There is, indeed, 

 some question, raised by Blume and Bennett, as to the order 

 of the development of the spiral vessels, but be the point de- 

 termined as it may, the medullary rays, reticulated articulated 

 leaves, dicotyledonous embryo, and, above all, the germination 

 properly understood, must be decisive as to real affinity. In 

 like manner the Menispermads were supposed to present an 

 endogenous structure, but if branches of sufficient age are ex- 

 amined, there is no question about the case ; and even were 

 this not the fact, the whole structure of the embryo would 



