1909] CURRENT LITERATURE 479 



Some of the ecological results are as follows. Ruppia is called a water halo- 

 phyte, living in salt water that would produce plasmolysis in fresh-water plants, 

 but unable to live in water of the open ocean. The hydrophytic responses of the 

 shoot are the weak and spreading form, the absence of stomata, the production of 

 slime, the numerous air spaces, the lack of mechanical tissue, and the reduction 

 of the vascular system to one axial bundle and two lateral ones in both stem and 

 leaf. The responses of the root are a reduction of the system to small unbranched 

 roots borne singly at the nodes, the presence of air spaces, and the concentric 

 axial bundle. The axial and cortical bundles are thought to be useless hereditary 



structures. 



Some of the facts in reference to the reproductive structures are as follows. 

 The inflorescence is a reduced spadix, and a small spathe is present, which is said 

 to have escaped the notice of investigators almost entirely. In the development 

 of the microsporangium a large archesporial group of cells is differentiated, which 

 later becomes septate. In the development of the megasporangium, usually 

 only one layer of parietal cells is formed, and in one case two functioning mother 

 cells were observed in a sporangium. The count of chromosomes was made in 

 the microsporangium and in the reduction divisions of both gametophytes, and 

 was found to be eight and sixteen. The male cells are produced before pollina- 



tion, which is accomplished by means of the water. The endosperm is scanty, 

 never being more than a thin layer lining the sac. The proembryo is a filament 

 of three or four cells, the basal one becoming much enlarged to form the suspensor- 



ree embrvo-formin 



termi 



of the proembryo, the two other cells producing the hypocotyl, adventitious root, 

 and primary root, the last organ never functioning. 



The paper contains a large amount of information in reference to a very 

 interesting form, and the plates, some of them photomicrographs, reproduce the 

 structures in such a way that every botanist can make his own interpretations. 

 —J. M. C. 



Orchid flowers and formative stimuli.— As a product of his visit of three 

 months at the Buitenzorg Garden, Fitting published in the initial number of 

 the new Zcitschrijt jiir Botanik an account of his experiments on the effect of 

 pollination and other stimuli upon the postfloration behavior of the flowers of 

 orchids. 22 The tropical orchids, available in great abundance at this garden, 

 are especially suited for experimental study on this point, because the difference 

 in duration of pollinated and unpollinated flowers is sufficient to give opportunity 

 for experimentation with unequivocal results, whether the postfloration processes 

 are autonomous or induced. Of these processes he distinguishes four : (1) pre- 

 mature fading; (2) closure of the stigma and swelling of the gynoptemium ; 

 (3) swelling of the ovary; (4) greening of the perianth. 



22 



Fitting, H., Die Beeinflussung der Orchideenbluten durch die Bestaubung 

 urch andere Umstande. Eine entwickelungsphysiologische Studie aus den 



und durch andere Umstande. 



Tropen. Zeits. Bot. 1 : 1-86. Jigs. 27. 1909 



