244 MEMOIRS OV THE NEW YORK BOTANICAL GARDEN. 



exceed the usual length, except in a few instances in which the 

 basal ones were slightly longer than the corresponding members of 

 normal stems. The upper internodes failed to reach the normal 

 length by such amount in stems showing this reaction, that the ordi- 

 nary length of the axis was not exceeded. In some species etiolated 

 stems were thicker than the normal, due to exaggerated development 

 of cortical or parenchymatous elements, both in size and number, 

 and the angular contour was more or less completely lost, the ten- 

 dency being shown toward an isodiametric section. The advance 

 from the embryonic condition reached various stages, but in no 

 case was the differentiation and construction of the elements com- 

 pletely normal. The primary annular and spiral vessels approached 

 the normal in structure perhaps more nearly than any of the elements,. 

 but these generally showed altered dimensions of the lumina with 

 thinner walls. Tissues with purely mechanical functions were more 

 reduced than other forms. The rigidity of the etiolated stems was 

 thus dependent upon the turgidity of the delicate and incompletely 

 formed tissues, and they were consequently fragile and easily dam- 

 aged by bending or mechanical contact. Branching was not shown 

 to any extent and the shoot was seen to consist of a single stem bear- 

 ing the reduced leaves. In some instances basal branches ordinarily 

 having a propagative function were produced, and if Solatium might 

 be included, it may be said to be the only species capable of forming 

 reproductive bodies of any kind when etiolated. It is to be seen by 

 reference to page 222 that the reactions of the climbers agree with 

 those exhibited by the species included in the above group. 



Exaggerated elongations of the stem are shown by Botrychium 

 obliqtium^ Brassica canipest7'is, Delphinium cxaltaiiim, Hydrastis 

 Canadensis^ Lysimachia terrestris, Pastinaca saliva^ Podophyllum 

 pcltatum^ Trillium crcctuni and T. erythrocarpum, and Viola 

 rostrata. The excessive growth to which this elongation was due 

 was variously distributed. Exaggerated growth in length took place 

 in all of the internodes of Brassica and Lysimachia, and through- 

 out the entire stalk of Hydrastis. The basal internodes of Del- 

 phinium and Viola were most elongated, although some excessive 

 lengthening occurred in all of the stems, while in Botrychium the 

 increase over the normal was found entirely in the upper part of the 

 stalk, the lower portion being somew^hat shorter than the average. 

 Branching was much reduced from the normal habit. The develop- 



