402 Prof. Hillhouse, Some Observations [May 28, 



grains swell in one way. This is especially the case with alcohol 

 grains, swelling, as will shortly be described, in method 5. In one 

 carefully watched case with dry grains treated with the reagent, as 

 the earliest result of the action of the reagent 1 took place for 

 some time alone, then appeared 2, and these two methods went on 

 together. Later occurred here and there a case of 3. Last of all 

 were a few grains only which swelled in the method 5. In this 

 preparation no case of 4 was observed. 



The method 4 is itself specially interesting. It is very infre- 

 quent, but I followed with great care, and drew at short intervals, 

 several cases of it. Outwardly it greatly resembles 3, with which, 

 in observation not of the closest and most continuous kind, it would 

 not unnaturally be confounded. The grain swells to a certain 

 depth, the swollen part being distinguished from the rest by its 

 refractive index, and a clear limiting line which cuts it off inter- 

 nally; This limiting line slowly moves inwards. Another less 

 turgid ring may be sometimes seen inside this one. The outer, 

 boundary of the grain is a strongly denned dark line. Suddenly 

 this zone ruptures at some point, and from that point dissolves 

 rapidly away in both (all) directions round the grain, till it has dis- 

 appeared. The residual grain has the same dark boundary line 

 and resisting limiting layer as before, and its boundary appears 

 dark immediately on the solution of the outer layer from that part, 

 and therefore progressively round the grain (Figs. 1 and 2). In 

 this method of solution slight signs of lamination are usually visible 

 in the surrounding fovilla (Fig. 1). 



Leaving for the present any discussion of these phenomena, let 

 us consider those observable in the case of starch which was first 

 merely damped with alcohol. The grains themselves closely re- 

 semble those of the tannin preparations ; stratification is rarely 

 visible. 



On addition of Chlorzinc Iodine no change is immediately 

 visible, but in the course of a minute or two the grains begin to get 

 feebly yellowish-red round their margins, and gradually, in a few 

 minutes, the whole grain becomes a very pale yellow-red 1 . Here 

 and there a grain gradually changes this colour to a rusty red ; 

 not uniformly, but with irregular patches of paler colour. The 

 nucleus sometimes becomes more clearly visible, as also does the 

 stratification in its immediate vicinity. With careful focussing so 

 as to get an optical section of some one particular grain, the outer 

 layer appears usually of a deeper rust colour, and a double outline 

 to the grain can in some be clearly seen (Fig. 3). Sometimes for 

 several hours there is no further change in the state of the prepa- 

 ration, excepting what is involved in the deepening of the colour, 

 and, with individual grains, its gradual modification into a more 

 1 Cf. Nageli u. Schwendener, Das Blikroskop, Zweite Aufl. S. 514. 



