348 



SGIENGE. 



[N. S. Vol. II. No. 37. 



plainly radial structure, and more or less clearly 

 marked striations, and whicli shows a cross 

 when viewed with a polarizer. These bodies 

 exist in the mineral, animal and plant kingdoms, 

 and may be artificially produced from organic 

 or inorganic material. The author claims that 

 the starch grains are sphserocrystals which are 

 exactly similar in structure and action to those 

 of other carbohydrates, with the single excep- 

 tion of their manner of swelling in the forma- 

 tion of paste. This difference he attributes to 

 the peculiarity of the /3 — amylose crystals, and 

 says it is too unimportant to make a distinction 

 between the starch grain and the sphserocrystal. 

 The typical sphserocrystal consists of very fine, 

 long, needle or thread-like crystals which may 

 be called trichiten. These trichiten are united 

 in clusters and the clusters branch in such a 

 manner as to form pores or channels for the 

 entrance of water. The manner of branching 

 depends upon certain conditions in the way the 

 material by which the crystal grows is furnished. 

 The appearance of stratification is caused by the 

 diflTerence, in the size of the pores, and conse- 

 quently the amount of water in the different 

 layers. In all this the starch grain corresponds 

 to the sphserocrystal of the pure amylodextrine, 

 both bodies enlarging to a certain extent on 

 taking in water. It is otherwise when heat or 

 chemical reagents are used, by which the starch 

 grain is partially dissolved. This he terms 

 ' Losungsquellung, ' a process peculiar to starch 

 and due to the nature of P — amylose. In con- 

 clusiou he adds, as the structure of the starch 

 grain corresponds to that of the sphserocrystals 

 of other carbohydrates it is highly probable that 

 it grows in the same manner. 



The result of the author's investigations con- 

 cerning the biology of the starch grains must 

 also be condensed into a few sentences. He de- 

 scribes the chromatophore as a drop of a com- 

 plex viscous fluid solution. In the viscous fluid 

 of this drop the carbohydrates are formed and 

 eventually condensed to amylose, etc. The 

 form of the starch grain depends upon the form 

 of this drop. It is also influenced largely by 

 the diastase which is in the chromatoishore it- 

 self and works principally from the outside in- 

 ward so that the grain grows smaller by its action. 

 He claims that starch grains may be formed in 



the three different kinds of chromatophores, and 

 that in the angiosperms, at least, they never 

 originate free in the cell sap or cytoplasm. He 

 describes the chloroplast as consisting of a color- 

 less or yellowish substance, stroma, in which 

 lay drops of a chlorophyll-colored substance, 

 grana. He suggests that the latter form the ap- 

 paratus of assimilation, while the stroma pro- 

 duces the starch and is also the organ by which 

 diastase is formed. The growth of the starch 

 grain is said to be influenced considerably by 

 the formation of crystalloids of proteid sub- 

 stances which the chromatophores are known to 

 form. He suggests that the names of the various 

 kinds of grains, given to them by Naegeli, be 

 changed to others more in harmony with their 

 manner of gro^vth. Numerous examples are 

 given from various plants, and the experiments 

 of a large number of scientists are quoted in ad- 

 dition to his own; to explain the cause of rifts 

 and clefts in certain grains, the origin of the 

 layers and many other points. 



Finally, he treats of the starch grain as a part 

 of the living protoplast. After contrasting the 

 views of Naegeli and Wiesner by which they 

 formulated hypotheses concerning the organiza- 

 tion of the cell, he says both these scientists 

 hold that there is no important difference be- 

 tween the structure of the starch gi-ain and that 

 of protoplasm. An entirely different relation, 

 however, between starch grain and protoplast 

 must be assumed by all who consider the proto- 

 plast a fluid. He then quotes from a large 

 number of scientists who agree with him in this 

 opinion of protoplasm. 



If this view of the nature of the starch grain 

 be correct, the commonly accepted theory con- 

 cerning the unit of structure of cell wall and of 

 protoplasm loses its foundation. It is true that 

 the greater part of Naegeli' s studies was con- 

 fined to the starch grain, while other botan- 

 ists applied these conclusions to the structure 

 and manner of growth of cell wall and even to 

 the unit of structure of the living protoplasm. 

 It is highly probable that, as a German botanist 

 said to the writer of this review, referring to an- 

 other contested physiological problem, "The 

 last word concerning this subject has not been 

 spoken." 



Emily L. Gregory. 



