60 Prof. Meyen's Report of the Progress of 



covered on the stems of the tree ferns, and of which mention 

 was made in our Year's Report for 1834, in which I already 

 suggested that it was possible to explain the cells of these or- 

 gans as impel feet nuclei [?J, (Brutkorner.) In the Lichens it is 

 theSoredicCy and in thejungermannice the leaves bearing the re- 

 productive granulations, which are regarded as formations ana- 

 logous to the lenticular glands of the more perfect plants. "The 

 design of the lenticular glands evinces itself," says Unger, "un- 

 doubtedly in the clearest manner in the formation of the im- 

 perfect buds of the Jungermannice, and hence we might form the 

 supposition of explaining the lenticular glands as efforts to con- 

 tinue on the cortex of dicotyledons the formation of imperfect 

 buds." Unger however thinks that a far greater design lies at 

 the bottom of all this; he observed that the lenticular glands de- 

 velop themselves on young shoots oi Prunus Padus and Si/ringa 

 indgaris exactly at those places where the stomata rarely occur, 

 and therefore the lenticular gland may stand in some way in con- 

 nection with the respiratory process ; nay, he would even con- 

 sider them as obliterated respiratory organs. 1 must also ex- 

 press a similar opinion as to the design of the lenticular glands ; 

 I consider them not as obliterated respiratory organs, but as 

 formations, by means of which an open communication is 

 made, intermediate between the exterior air and the intercel- 

 lular passages of the green layer of cortex. In this latter 

 tissue intercellular passages are very frequent; but the firm 

 combination of the cells in the exterior layers of cortex do 

 not allow in the old state of the plant of any uninterrupted 

 communication. 



Link* also contends that the lenticular glands belong tcf 

 the cortical formation, that the temporary roots, on the con- 

 trary, originate from subjacent wood ; yet it cannot be denied 

 that they break out for the most part near to these warts, as 

 also do the shoots. 



Very interesting is an observation of Eudes-Deslongchampsf 

 on theefFect which the circular decortication produces upon the 

 vegetation of a tree ; similar experiments it is true have been 

 previously made with the same results ; but the present one 

 of Eudes-Deslongchamps, which was performed on a beech, 

 has been observed very carefully. The wound of the cortex 

 which went round the whole circumference of the stem was 

 nearly a foot wide, and the vigorous tree seemed not to 

 suffer in the least by it. On the surface of the decorticated 

 vood were to be seen many irregular exudations which had 



• Elcm.Phil.Bot.,^.2H\. 



t I^els de la decortication circulaire sur uti Heire. — VInstitut de 1836, 

 p. 314. 



