CURRENT LITERATURE 



Senile Changes in Leaves of Vitis vulpina L. and Certain Other 

 Plants. By H. M. Benedict. Memoir 7, Cornell University 

 Agrictiltiiral Experiment Station. Ithaca, N. Y. 1915. Pp. 89. 



Investigations have established the occurrence of fairly definite 

 senile changes in animals, but very little work has been done in 

 the attempt to demonstrate the presence or absence of such changes 

 in plants. The latter condition of affairs may be due to the pas- 

 sively assumed belief that woody perennials, such as trees, be- 

 cause of their annual renewal of tissue through the agency of 

 persisting embryonic cells, would be immortal, were it not for the 

 inimical conditions contingent upon their increasing size, such as 

 liability to breakage and thus to disease infection, distance from 

 the soil, exposiu-e to excessive water-loss, and so forth. To quote 

 the author: "The importance of determining whether there is any 

 real senile change in plants lies not alone in the scientific need of 

 such knowledge, but also in its direct bearing upon the long dis- 

 puted question regarding the effect of continuous vegetative 

 propagation of seed-producing plants. For, if the new growth 

 from which cuttings are made, has not been affected by the time 

 that has elapsed since the plant came from the seed, then its tissue 

 is no more senile than the seedling tissue ; if, however, the embry- 

 onic tissue which has been so actively growing and dividing since 

 it originated from the parent plant, has itself suffered the senile 

 deterioration that accompanies activity in animal cells, then the 

 tissues arising from this embryonic tissue must partake of its 

 senility." 



The greater portion of the author's investigations was made 

 upon the leaf of the wild grape. About 20 pairs of vines of differ- 

 ent ages, growing in similar conditions were selected and 10 leaves 

 were taken from each pair. Care was taken to get fully matured 

 healthy specimens. Each set of pairs was taken from the same 

 height and as nearly as possible in the same light exposure. The 

 size of the meshes of the photosynthetically active cells lying be- 

 tween the network of veinlets was taken as a standard. These 

 areas are called vein islets. The size of the vein islets was deter- 

 mined by means of enlarged photographs. The author found 

 that the size of the vein islets decreased with the increasing age 



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