388 



Dr. W. J. Kussell. The Action of [June 19, 



different seeds and fruits. The outside is quite inactive ; even if laid on a 

 plate for a long time it produces no effect. The horse chestnut is apparently 

 an exception, but in this case the outside skin of the nut is very thin, and 

 the brown material immediately beneath it is very active, but the nut itself, 

 as before stated, is quite inactive. 



With regard to the woody substance which forms the substance of a shell 

 it consists of at least two distinct substances, one of which is able to act on 

 a plate, and the other is not able to do so. 



For instance, in a cocoanut shell, the constituent of the shell which is 

 lightest in colour is quite inactive, and the darker part is very active. 

 Again, in the butter nut, fig. 2, the red portion of the shell is quite 

 inactive, while the dark part is strongly active. In the Brazil nut the 

 same thing also occurs, the central dark layer being very active, and the 

 outside part is entirely without action. In fir cones the same kind of thing 

 occurs : the axis of a cone consists of materials varying but slightly in 

 colour, but very considerably in their power of acting on a plate. In the case 

 of the almond shell it is throughout perfectly inactive. 



Both the shell of the acorn and of the Barcelona nut consists of two layers, 

 which are easily separated ; the outside one is inactive and the inside one is 

 active. Immediately within the shell of a nut there are one or more 

 integuments, and they have very different powers of acting on a plate. For 

 instance, in the cocoanut there are three integuments, the one next to the 

 shell is very thin and of a whitish colour, the next one is much thicker and 

 of a brown colour, and the third one is very thin and also brown in colour. 

 The thin integument next the shell and the thick brown one in contact with 

 it are both active, but the third layer is without activity. There is also a 

 thin skin adhering to the kernel ; this is also quite inactive. This variation 

 in the action of different parts of a nut is well shown in fig. 3, which 

 represents the two halves of a walnut split through the middle ; from one half 

 the kernel has heen removed, but not from the other half ; the kernel filling 

 up the shell is quite inactive, but the lining to the empty shell is very 

 active. 



Actions of the same kind occur with broad and runner beans and other- 

 seeds ; the outside, the testa, is inactive and the inner layer is active. 



Fig. 4, Plate 19, is a picture given by a section of a broad and a runner- 

 bean, and fig. 5 a section of a horse chestnut. 



On examining the flowers of different plants the petals in all cases have 

 been found to be active. They are best dried by squeezing between Ford 

 blotting paper, and a picture can be obtained both from the petal itself and 

 from the expressed juice in the paper. In many cases a characteristic picture 



