116 Ph3'siologie 



The Plasmodium derived from the tapetum sends fingerlike 

 processes into the sporangium between the separated sporogenous 

 cells. These at first are only cytoplasmic but later on nuclei pass 

 into them; while passing in these become elongated but again resume 

 their isodiametric form on Coming to rest, The average size of the 

 nuclei is fairly constant. At this stage the Plasmodium is rieh in 

 starch but the sporewalls are thin and their protoplasm scanty, The 

 spores are tetrahedral and possess three ridges which converge to 

 a point. The endospore which gives pectic reactions arises within 

 the cuticularised wall and forms a continuous layer over its inner 

 surface; it is not derived by the differentiation of the sporewall 

 but is probably a new formation. At the apex of the spore it pushes 

 between the ridges of the exospore and reaches the surface. Later 

 a reticulate sculpturing is formed on the exospore; no epispore 

 is present. 



During the formation of the spore coats the spore cytoplasm 

 is scanty and poor in starch, but some starch is found in the ripe 

 spores. Meanwhile the tapetal cytoplasm begins to decrease in amount 

 and to lose its starch; the vacuoles which are surrounded by very 

 distinct plasmatic membranes increase in size and, finally, when the 

 spores are ripe, the plasmatic membranes become completely approxi- 

 mated owing to the almost total disappearance of the cytoplasm. 

 While this is going on the tapetal nuclei which are rieh in chromatin 

 often become irregulär in shape. The author therefore concludes 

 that the tapetal Plasmodium is the centre of metabolic activities in 

 which a substance is elaborated from the raw materials contained 

 in the tapetum and that this substance is directly or indirectly 

 employed in the growth of the sporewall. 



M. Wilson (Glasgow). 



Ewart, A. J., The Influence of Correlation upon the 

 Size of Leaves. (Annais of Botany. Vol. XX. 1906. p. 79—82. 

 With two textfigures). 



The author refers to Lindemuth's Statements regarding the 

 size of leaves of Begonia rex and Iresine Lmdeni which have been 

 allowed to root in soll. Experiments performed on Tilia eiiropaea are 

 described. All buds except the terminal one were removed from a 

 branch in spring; the leaves of the remaining bud developed to an 

 abnormally large size. The cells were of the normal size and the 

 enlargement was due to an increase of the number of cells formed. 

 On subsequently removing all except the first and second leaf no 

 increase of size occurred in the latter. All the leaves, except those 

 of the terminal buds, were removed in June from two branches. In 

 one case no subsequent increase of the remaining leaves took place. 

 In the other a vertical glass tube was attached to the cut-surface of 

 a lateral branch near the apex and a pressure of from 6—10 ft. of 

 water was maintained for a month , but no enlargement of the leaves 

 was obtained. 



He concludes that neither the effect of an unusually abundant 

 supply of water nor of correlative influences due to the removal of 

 other buds and leaves are able to excite renewed growth in adult 

 leaf of Tilia ^ even when acting conjointly. These influences, possibly 

 aided by a more abundant supplj^ of food, do, however, cause leaves 

 to develope to an abnormall}^ large size when applied at a sufificientty 

 earty period of their growth. M. Wilson (Glasgow), 



