Occurrence of Foliage-kaves in Ruscus androgyaus. 141 



" needles " of Sciadopitys to the ftjUowing effect : — The 

 needle makes its appearance within a short distance of the 

 growing point of the main axis ; but not until the axillant 

 scale-leaf is somewhat advanced in its development, and is 

 beginning to form its single mesial vascular bundle. In 

 its earliest stage, the needle is a uniformly rounded 

 elevation from the axis, somewhat flatly compressed, but 

 " otherwise exactly like an ordinary axillary bud." Very 

 soon, however, it exhibits an evident cleft at the apex, 

 followed shortly afterwards by a slightly-marked furrow on 

 the under side. Beyond this first stage, apical growth of 

 the organ is no longer to be observed. Its further rapid 

 increase in length is only by intercalary cell-divisions, 

 especially at the base. The cleft at the apex is much more 

 striking in the young needle than in the older one ; 

 since the apex remains almost unchanged, while the 

 needle increases notably in length. At a later period, 

 the furrow on the under side becomes more pronounced, 

 while a shallower one appears opposite to it on the upper 

 side. The formation of the two vascular bundles com- 

 mences when the needle measures about 0"65 mm. in 

 length. From each of the two nearest stem-bundles, above 

 the insertion of the axillant scale-leaf, a bundle is given 

 off ; and these are pretty quickly differentiated from below 

 upwards in the needle. Strasburger concludes that we 

 have here to do with an- axillary bud, and that, moreover, 

 the development shows that the union of the two leaves of 

 this bud reaches back (zuriickgreift) to the first stages of 

 their development, so that at no time thereafter is it possible 

 to observe a punctitm vegetationis between them.* It will be 

 seen from the foregoing, that Strasburger's view closely ap- 

 proximates to that of Von Mohl. Only, that Strasburger 

 (as I understand him) holds the two leaves to be united by 

 their inner (upper) faces, the abortive punctuvi vegetationis 

 being buried and lost between their bases ; while on Von 

 Mohl's hypothesis the abortive puncium would, I presume, 

 be external on the anterior aspect of the bases of the two 

 leaves supposed to be united by their posterior margins. 

 With regard to the developmental evidence, however, there 

 seems to be nothing whatever to prove that the arrested 



* Strasburger, Die Coniferen uml die Gnctacecn, Jena, 1872, pp. 385-86. 



