32 MEMOIRS OF THE NEW YORK BOTANICAL GARDEN. 



Brenner ^^^ attributed the abnormal forms of succulent species of 

 seed plants in darkness to disturbances of transpiratory conditions on 

 one hand, in addition to an adaptive elongation of the shoot for the 

 5)urpose of reaching the light. 



The investigations of Thomas"^ in w^hich instructive comparisons 

 were made between the characters of subterranean and aerial leaves 

 are of great interest. Leaves normally or experimentally developed 

 as underground scales cutinize both upper and lower surfaces, and 

 diminish the formation of collenchyma, palisade cells and intercellu- 

 lar spaces. Decrease in vascular tissues, disappearance of projec- 

 tions and irregularities of contour, diminished development of sieve 

 tubes and stereome are also features of such growth, and are parallel 

 to those shown in etiolation. Underground leaves may also lose the 

 stomata when used for storage. 



Maige "* brought out some interesting observations on the geo- 

 tropic reactions of creeping plants in darkness. Two groups are dis- 

 tinguished according to their reaction in darkness. One group, 

 including Hicracitim filosella 2ind Mentha saiiva, places its branches 

 in an erect position in darkness, and a second, of which Potentilla 

 replans is representative, does not. 



Stigeoclo7iium tcniie has been found to remain green and healthy 

 in darkness for periods of three to five weeks, and such deprivation 

 of illumination did not alter the response to the osmotic and nutritive 

 influence of solutions, according to the observations of Livingston, ^^^ 

 an endurance which is of interest in connection with the determination 

 of the term through which chlorophyl may be maintained in darkness. 



Goff '"' relates that the first node of seedlings of corn usually is to 

 be found near the surface of the soil, regardless of the depth at 

 which the seeds may be planted. Seedlings in darkness showed 

 such elongation of the first internode that the node was raised some 

 distance above the soil. 



'12 Brenner, W. Untersuchungen an einigen Fettpflanzen. Flora, 87 : 387. 1900. 



'1^ Thomas, J. Anatomie comparee et experimentale des feuilles souterrainnes. 

 Rev. Gen. d. Bot. i2: 394. 1900. 



"■'Maige, A. Recherches biologiques sur les plantes rampantes. Ann. Sc. Nat. 

 VIII. II : 345. 1900. 



"5 Livingston, B. E. Further Notes on the Physiology of Polymorphism of Green 

 Algae. Bot. Gazette, 32 : 29S. 1901. 



"5 Goff, E. S. Influence of Light on the Length of the Hypocotyls in Indian Corn. 

 Science, 13: 395. 1901. 



