194 



PRINCIPLES OF PLANT-TERATOLOGY. 



row of strands, were two others on the dorsal- 

 (adaxial) side which were irregularly orientated, as if 

 the two foliar organs to which they belonged (repre- 

 sented by two conspicuous ridges), were undergoing a 

 certain amount of revolution or torsion preparatory to 

 their eventual more complete fusion, at a higher level, 

 with the main leaf. 



" Particular attention must be directed to the com- 

 parison which may be made between these curious 

 recurved leaves of the axillary shoot and the ordinary 

 'needles' of Sciad.opitys. . . . The recurved axillary 

 leaves of Finns Thunbergii (albeit abnormal) afford, 

 therefore, another case of vegetative leaves being formed 

 in this way, the case of Sciadointys being the only 

 normal one known. 



" Strasburger* described and figured a case of fusion 

 by their adaxial margins of the needles of Pinvs 

 Pumilio [and P. st/lcestris] ; Mr. L. A. Boodle has seen 

 similar fusion of needles [in P. Laricis var. austriaca] ; 

 the present writer has seen the specimens which he 

 collected. The fusion, however, was sometimes by the 

 adaxial and sometimes by the abaxial margins. 



" These cases of Pinus are not wholly comparable 

 with those of the recurved fleshy leaves of P. Thun- 

 bergii and with the 6 double needle ' of Sciadopitys ; 

 for the needles of Pinus are not the first-formed leaves 

 of the axillary shoot, being preceded by a number of 

 scale-leaves ; they may be also variously orientated, 

 a fact which will account for the variation in the 

 mode of marginal fusion. 



" The best comparison of all may be made between 

 our recurved leaf and the o villiferous scale of the 

 Abietinese, for, according to the most popular view 

 of the latter, the mode of origin of the two is precisely 

 identical. In both cases, also, one or two leaves 

 situated at a higher level on the axillary shoot have 

 become incorporated into the double foliar organ ; the 

 apophysis or umbo on the adaxial side of the ovuli- 



* Strasburger, 'Die Coniferen raid Gnetaceen/ 1872, p. 387. 



