1883.] on the Swelling of Sta?-ch Grams. 401 



that in the meantime many grains have swollen, and imperceptibly 

 disappeared, without coloration ; while others one can observe 

 to swell, split, and disappear, the outer layer of each sector of 

 the grain dissolving last, being visible to the end as an apparent 

 membrane, of which the free edges (ends in optical section) are 

 carried back by the swelling internal mass ; — this swelling and 

 solution likewise without coloration. The same process continues 

 for some considerable time (perhaps an hour) the chief signs of 

 staining being merely a violet-red rim to many grains. But it is 

 noticeable that many other grains which have shown none of 

 the common signs of swelling are perceptibly smaller, and that, 

 without any of the processes above indicated, the pulpy mass 

 around them has enlarged. Each of these solid reduced grains 

 preserves its shape and distinct outline, but the surrounding 

 pulpy mass takes a faintly violet tinge. The solid remnant still 

 shows sometimes nucleus and stratification. In twenty-four hours 

 . the preparation forms a homogeneous mass of dissolved starch, 

 with here and there only, a solid remnant. In some preparations, 

 however, after this period a few grains show the peculiar lamina- 

 tion illustrated in Fig. 8, and which will be hereafter more specially 

 dealt with. 



The fact that we had here evidently to do with not one, but 

 several distinct methods of swelling, made it clear that nothing 

 was to be done with merely periodical inspection. I therefore 

 kept a series of preparations each under continuous observation 

 for periods up to about three-quarters of an hour in length, with 

 resting intervals between these periods. In this manner the 

 following five methods of swelling could be distinguished : — 



1. The grain swells en masse, and resolves itself, without 

 rupture, into a mass of " fovilla." 



2. The grain swells en masse, then ruptures, and passes into 

 fovilla from the point of rupture. 



3. The grain swells from the outside to a certain depth, the 

 swollen part gradually dissolving off from the outer side, while the 

 swelling penetrates further inwards. A solid remnant of the grain 

 is therefore left, gradually and regularly diminishing by the pro- 

 gress inwards of the swelling. 



4. The grain swells from the outside to a certain depth, the 

 outer swollen part ruptures and passes into fovilla ; the remnant 

 again swells externally as before. Two concentric swelling rings 

 are sometimes visible. 



5. The swelling takes place by laminge, apparently equivalent 

 to the sheaths or " complexes of lamellse" of the grain. The whole 

 resulting swollen mass of the grain is laminated. 



Which of these methods takes place in a particular preparation 

 is apparently uncertain and irregular. Sometimes nearly all the 



