309 



Tliat no difference conlrl be found in the rate of nitrogen betweert 

 the granulose and the anijlopectose of the starcli grain, to which 

 circumstance I dii'ected attenlion in uiv comuiunication of Jl April 

 1912, I ascribe to the extreineiy small absolute rate of nitrogen in 

 both constituents ; but I think that the relative ditference is con- 

 siderable. 



I will not omit to draw attention to the existence of starch species, 

 which after heating, do not crystallise in the usual way. To these 

 belongs arrowroot. If a 10 "/o pasle of arrowroot is precisely treated 

 as above described, it becomes after cooling, as usually, turbid and 

 precipitates; but instead of a crystalline deposit we find in the 

 microscopic preparation drops of various sizes, and homogeneous struc- 

 ture (Fig. 4), which later, however, become turbid and granulous. 

 With iodine these drops turn deep blue and evidently consist of 

 granulose like the crystal needles of the oUier starch species. The 

 liquid between the drops is also a granulose solution, but less con- 

 centrated. The drops remind of a heavy oil, but they differ from it 

 by such a small surface tension that notwithstanding their liquid 

 state many may be pear- or egg shaped, and even pointed. Double 

 refraction I could not perceive, but, nevertheless, I think it probable 

 that they must be reckoned to the liquid crystals. That after some 

 time the drops become (urbid can be explained by the growing in 

 length and thickness of the ultra-microscopic needles, which constitute 

 the liquid crystal drops, hence, by the same process of crystallisation 

 by which the needles originate. 



The facts here briefly described deserve further attention from a 

 physico-chemical view. 



EXPLANATION OF THtl FIGURES. 



Fig. 1 (600). Spliero-crystals of 10% potato starch, hall' an houi- at 150° C. 



Fig. 2 (600). Bolidiscs or Jacquelain discs of potato starch, half an hour at 

 125° G. 



Fig. 3 (230). Bolidiscs or Jacquelain discs of wheat starch, three quarters of 

 an hour at 160° G. 



Fig. 4 (200). Drops or liquid crystals of IO'/q arrowroot, three quarters of an 

 hour at 140° G., coloured with iodine. 



21 

 Proceedings Royal Acad. Amsterdam. Vol. XVIII. 



