291 QUARTERLY CHIIONICI.E OF MICROS^COPICAL SCIENCE. 



joints the medulla becomes reduced to a single large cell. 

 The terminal joints become attenuated, and often spine-like ; 

 in other cases, however, they become cellular, or end club- 

 shaped. In the formation of the cortex of the leaf-joints no 

 general rule prevails. The formation of " hairs ^' is restricted 

 to the axil of the leaf-tip. The leaves of Cladodephus branch 

 by a division of the apical cell similar to that of the axis in 

 Halopteris. 



Cladostephus possesses, besides vegetative *' leaves," a 

 second form of leaves, or '' fruit-leaves." These were re- 

 garded by their first observers as a foreign epiphytic growth, 

 and described by them under the name of Sphacelaria 

 Bertiana. They originate only at the end of the period of 

 vegetation on the old joints, after all increase in the thick- 

 ness has completely ceased ; their configuration is much 

 simpler than that of the foliage leaves. The outermost peri- 

 pheral cells of the internodes of the old joints are the 

 mother-cells of the fruit-leaves ; they grow out in a papilla- 

 like manner, and become the apical cells of these organs. 

 They ordinarily bear the sporangia on special " fruit- 

 branches ;" more rarely the apex of the fruit-leaf itself 

 becomes the fruit-branch. They are ramifications of the 

 undivided joint-cells, or, more usually, of the "innovation- 

 cells" of the lower and middle joints of the fruit-leaves. 

 These innovation-cells grow out laterally from the joints of the 

 fruit-leaf, and become the apical cells of the fruit-branches. The 

 number of their joints varies from one to eight. The resulting 

 uni- and multilocular sporangia are distributed on different 

 plants. The former are terminal, the apical cell increasing 

 in size, and its contents emerging en masse, enclosed in a 

 common mucus, presently breaking up into zoospores. The 

 supporting cell of the sporangium may continue growing 

 as a new apical cell, and thus the younger sporangia may 

 come to be surrounded by the empty coats of several older 

 sporangia. The multilocular sporangia are likewise terminal ; 

 the apical cell becomes divided into 3-5-celled series ; the 

 individual cells, by repeated vertical and horizontal divisions, 

 give rise to the mother-cells of the zoospores, one in each. 

 The zoospores are not emitted en masse, but each forms its 

 own mother-cell ; they do not appreciably differ from those 

 of the other kind of sporangium, and resemble those of 

 other Phteosporece. They possess two cilia — one, the longer, 

 directed in front, the other behind. 



About the end of November (at Genoa) the vegetation- 

 pause in Cladostephus commences. Some of the buds remain 

 dormant, and resume their growth the following year. This 



