132 Bulletin Jard. Bot. Buitenzorq, Série III, Vol. V. LivR. 2. 



lie shows the same air spaces in the iieck pièce which joins the young 

 seedling witii the haustorium. hi plate CGXXXA he has a figure which 

 although it is not labelled as such, is inidoubtedly a cross section of a root 

 with lacunae; the form is Arcca triandra. 



GOEBEL in (1886) called attention to the breathing organs of the marsh 

 plants Sonneratia and Avicennia. Thèse plants develop side roots which 

 are negatively geotropic and whose anatomical structure shows that they 

 fuiiction as organs of gas exchange. 



JOST C^j one year later published his observations on breathing organs 

 in plants based primarily on work with palms. For those organs he coined 

 the word pneumathode. Thèse pneumathodes grow upward, outgrowths 

 from larger roots. He found such organs in the following plants: 



Livistona australis, L. e/ii/icnsis, L. altissimu, L. nuuiritijormis, P. 

 olivacfonnis, Phoenix reclinata, P. silvcstris, P. dactylifcra, P. spinosa, 

 P. farinifera and other undetermined species. 



Pritchardia filainentosa 



Kentia Forsteriana 



Cliamaerops hiimulis 



Chamaedorea Veifcliii 



Cocos flexiiosa 



Caryota fiirfiiracea 



Thrinax species 



Pandaniis flexiiosus, P. pygmaciis, P. furcatus. 



JOST observed in Livistoii'i australis which was growing in a large 

 wooden tub, a large number of upright growing structures 2 — 4 mm. thick 

 and 5 mm. above the surface of the soil. A characîeristic mealy appearing 

 tissue either in the form of rings or covering the whole surface of the 

 protruding organs is described. Thèse structures are side branches which 

 arise endogenously from the larger roots. In their anatomical structure, lack 

 of epidermis and présence of a characteristic aerenchymous tissue, the 

 présence of large inter-cellular spaces in direct connection with the root, and 

 the fact that the root comes in contact with the air oiily through the pneu- 

 mathodes speaks for their function. Experiment showed that thèse pnema- 

 thodes were produced undergrond also. JOST showed thèse organs to coii- 

 tain a large amount of air. The cells of the mealy appearing tissue in cross 

 section are stellate in form. 



JOST observed similar pneumathodes \u Saccharnm, Cyperus fexÉilis and 

 Liiffa ainara Roxbhg. SCHENK f;*^) describes the présence of dimorphic 

 roots in the mangrove plants Avicennia tomcntosa and Laguncnlaria racemosa. 

 The structure of thèse and other mangrove plants is too well knowii to 

 bear répétition hère. However, mention must be made of the origin of the air 

 passages through schizogamy and lysiginy For a detailed considération of the 

 aerenchymaof marsh plants, wich we shall not consider hère but in a later publi- 

 cation, référence should be made to another publication of SCHENCK's (^•*). 



