74 



Devaux in exceptional cases, cell-division followed the 

 abnormal growth. 



The growth of the pehlloderm cells takes place most 

 vigorously in a radial direction,- elongated cells, similar 

 to sausages in form, are produced, v/hich often lose all firm 

 connection with one another in their longitudinal walls and 

 remain connected only by their tangential walls. They form ' 

 lose cell rows, paralell to one another and arranged radial- 

 ly, which curve out on the surface of the lenti eel- out growth 

 in flat undulations, and often separate into their individual 

 elements. In other cases the elongation in a radial direc- 

 tion is omitted and the cells remain spherical. 



The degree of hypertrophic enlargement varies not only 

 in different species hut also in lenticels of the same 

 species. At times the growth of the individual cells is very 

 slight, in which case the changes of the lenticel tissue 

 consists principally of a breaking up, or a complete macer- 

 ation of certain layers. It v/as not investigated more close- 

 ly to see how far external factors influence the mass of 

 hypertrophic growrth. 



Lenticel outgrowths of the kind described may be ob- 

 tained in the most varied specimens: roots and shoots bear- 

 ing lenticels form in an equal degree excresences resembling 

 aerenchyma. The lenticels of the potato tubers, the lenti- 

 cels of the leaf galls of Uematus gallarum , v;hich lives on 

 the willow, etc, , may easily be brought to the formation of 

 excresences. The age of the lent icell-b earing organ con- 

 cerned is of no importance; I found young shoots of Popu- 

 lus , Catalpa, Solanum tuberosum and others, cultivated in 

 a moist place which developed lenticels and lantscel excres- 

 cences in the immediate vicinity of the growing tips of the 

 sprouts. 



The v/orks of v. Tulrbeuf and Devaux throw light on the 

 plants, on which lenticel-excresences have already been 

 observed, 



Bevaux observed hypertrophied lenticels on the shoots 

 of the following plants: 



(77) 



Ampelopsis quinquefolia, 

 Acer Negundo, 

 Alnus glutinosa , 

 Broussonetia papyrifera, 

 Coriaria myrtifolia, 

 Cydonia vulgaris , 

 Diervilla grandiflora, 

 Paphne GnidiiMri 

 I). Laureola, 

 Fraxinus excelsior , 

 Ficus Carica, 

 F. elastica^ 

 Gleditschia triacanthos , 



Hedera helix, 

 Juglans regia, 

 Jasminum officinale, 

 Ligustrum vi^lgare, 



Marsdenia erecta, 

 Malus communis , 

 Morus alba , 

 Pelargonium zonale , 

 Plat anus vulgaris , 

 Pirus communis , 

 Prunus div. sp. 

 Quercus pedunculata , 

 Ribes rub rum , 

 Robinia pseud-acacia , 

 Salix div. sp, 

 Sambucus nigra, 

 Spiraea lanceolata , 

 Syringa vulgaris , 

 Tilia si'iv^stris7 

 Ulmus cami|l6tri"s7 

 Weigelia I Qg'^a, 



