INVERTEBRATA, CRYPTOGAMIA, MICROSCOPY, ETC. 677 



Bilateralness in Floridese.* — In contradistinction to the ordinary 

 multilateral structure of the Floridefe, some instances of bilateral 

 structure have been described by Nageli and Kny in the genera 

 HerposiiiJionia and Basya. These and other examples have now been 

 more closely examined by Ambronn. 



The nature of the bilateralness is different in these two genera ; in 

 the former we have an instance of monopodial, in the latter of sym- 

 podial ramification. 



In the first species described, Bytiphloea pinastroides, the apex of 

 the stem is strongly curved inwards, the axis of the stem grows by 

 means of an apical cell from which nearly cylindrical segments are 

 cut off, breaking up into five peripheral and one central cell. The 

 lateral organs are leaves and axes. The leaves stand in a single piano 

 upon the convex, tlie axes in two planes on the concave side. The 

 leaves have a limited, the axes in general an unlimited power of 

 growth. The former consists of undivided, the latter of segmented 

 cells. The leaves branch in a pseudo-dichotomous manner, the 

 number of ramifications being at most six ; the ramification of the 

 axes generally proceeds to the fifth order. Growth by enlargement of 

 the cells commences in the leaves at the apex, advancing to the base, 

 in the axes in the reverse order. Both those divisions by which the 

 segments break up into five peripheral and one central cell, and those 

 which result in the formation of the cortex, commence on the convex, 

 and advance equally on both planes to the concave side. 



Bytiphhiia tinctoria differs from R. pinastroides ma,inlj in the outline 

 of the stem being elliptical instead of circular. The branching also 

 goes on to the seventh degree. 



In Eelicothamnion scorpioides the axis has a strongly incurved cone 

 of growth as long as it is in active growth. The lateral structures are 

 exclusively axes, and stand alternately right and left. All the ramifica- 

 tions lie in one plane, which intersects the primary plane in the axis of 

 growth of the primary shoot at right angles. The ramification usually 

 proceeds to the sixth degree. The stem grows by an apical cell, from 

 which cylindrical segments are separated, each of these breaking up into 

 from four to seven, usually six, peripheral and one central cell. Each 

 of the former then divides again by a septum, the commencement of 

 the cortical structure. The primary axis lias unlimited, the lateral 

 axes limited growth. 



In Ilerposiphonia fenelln and scciindn the axes and the short shoots 

 (Kurztricbcn) grow by means of an apical cell which is repeatedly 

 divided by septa; the number of segments is indefinite in the long, 

 definite in the short shoots. Eacli segment breaks up by longitudinal 

 divisions into peripheral cells and acentral one, the nuinberof the former 

 sometimes amounting to as- many as twelve. The lateral structures 

 on the axes are of three kinds, root-hairs or rhizoids, lateral or long 

 shoots, and short shoots. Tlie rhizoids arise from the first pcriphoml 

 cells of the axes, and henco on tlieir convex side. The long and short 

 shoots are formed from the undivided cells in strict ncropctal succes- 



• • l{..t. Z. it..' xxxviii. (iKMt) p. l»;i. 



