September 13, 1895.] 



SCIENCE. 



347 



amylose, and says it is quite possible that future 

 investigations will show that /?- and a- amy- 

 lose are crystals of one and the same substance, 

 the former containing water, the latter without. 

 Of the difference between them, he says /3- 

 amylose is soluble in water at 100°, while a- 

 amylose requires a greater degree of heat to 

 render it soluble, and that if the starch grain be 

 treated with water at 138° a single substance 

 may be obtained in the form of /3- amylose as 

 the a- amylose is changed to this form. 



Amylodextrine is said to be of interest for 

 three reasons. First, it exists in those starch 

 grains which turn red with the application of 

 iodine ; second, the ordinary starch grain can 

 be easily changed into it ; third, because the 

 sphserocrystal of the pure amylodextrine is very 

 important in explaining the real nature of the 

 starch grain. The first discoverer of amylodex- 

 trine was Musculus (Comptes rendus 1870, page 

 857), who named it insoluble dextrine. Its 

 present name was given it by Walter Naegeli, 

 who, vnth many other scientists, afterwards ob- 

 tained this substance by treating starch with 

 various acids. The author conducted a series of 

 similar experiments for the purpose of obtain- 

 ing amylodextrine in a j)ure form and then to 

 determine its molecular weight. He succeeded 

 in the former, but in the latter attempt only 

 learned with certainty that its molecular weight 

 was very high. He then gives in detail the ex- 

 act methods and results of a long series of ex- 

 periments with various substances more or less 

 clearly related to amylodextrine. Among other 

 conclusions concerning it he states that the 

 skeleton of the starch grain, obtained by treat- 

 ing it with saliva or acids, does not consist en- 

 tirely of amylodextrine as was formerly sup- 

 posed, but of a mixture of crystals of this sub- 

 stance with crystals of a — amylose. Part first 

 closes with the macro- and micro-chemistry of 

 the starch grain. 



In the second chapter he gives a statement of 

 his conclusions concerning the physical constitu- 

 tion of the starch grain, with an explanation of 

 his reasons, then a full account of all the theo- 

 ries preceding his own. It is impossible to 

 give more than a brief summary of the con- 

 tents of this chapter in the space allotted to a 

 review. 



Naegeli's theory, as the author states, was 

 the first which was founded on an extended se- 

 ries of observations, and from the year it was 

 published, 1858, till now, it has been the pre- 

 vailing theory with most scientists and text-book 

 writers. According to our author, however, it 

 has wrought much harm by introducing the use 

 of the terms, intussusception and apposition as 

 applied to methods of gro^vth, also by the appli- 

 cation of the supposed manner and growth of the 

 starch grain to that of cell wall and protoplasts. 

 Schimper, in his work published in 1880 and 

 1881, was the first to destroy the deep-seated 

 faith in Naegeli's theory. This he did first, by 

 proving that most starch grains are formed in 

 the chromatophores, while the foundation of 

 Naegeli's theory rests on the assumption that 

 the starch grain grows free in the cell sap. 

 Second, Schimper claimed that the inner part 

 of the grain is the older, the outer the younger. 

 His conclusion is that the starch grain is a sphse- 

 rocrystal composed of fibrous crystalloids, there- 

 fore the whole is a crystalloid. The author 

 contrasts the opinions of Naegeli and Schimper 

 as follows : Naegeli supposed the grain to be 

 made up of long crystals lying perpendicular to 

 the layers of stratification, but free in the cell 

 sap. Schimper supposed the crystalloid threads 

 composing the grain to be united at their bases. 

 Naegeli made the spherical bodies or balls, form- 

 ing the transition between fluid and solid bod- 

 ies, grow by means of the intercalation of new 

 substances between the old particles ; Schimper, 

 by the superposition of new masses of substance. 

 Naegeli explained the layers as resulting from a 

 difference in tension caused by the new parti- 

 cles of substance intercalated between the old, 

 Schimper, by a difference in tension caused by 

 the influx of water between the particles of sub- 

 stance. It is in this particular, and in other 

 characters of the grain which Schimper claimed 

 as a cause for its striations, that his theory dif- 

 fers from that of the author. 



According to the latter, the starch grain is a 

 sphserocrystal (not a sphserocrystalloid) com- 

 posed of crystals of /3 — and a — amylose and 

 amylodextrine. He defines the word sphsero- 

 crystal in the sense in which it was used by 

 Naegeli and Rosenbusch, that is, a microscopic- 

 ally small spherical body with a more or less 



