PHYSIOLOGICAL BOTANY. 245 



were, gelatinous. For as soon as sulphuric acid is added to 

 the granules of starch, under the microscope, and it begins 

 to remove the water from the inner layers, a bubble of air 

 appears in the place of the nucleus ; the same occurs when 

 the granule of starch is heated ; in fact, even when fresh 

 starch is dried at the ordinary temperature of the air. 

 The latter phenomenon, which was not observed by either 

 Schleiden or Fritzsche, thus also explains the formation of 

 the fissure near the nucleus. But if, as appears from 

 these observations to be the case, the nucleus and the 

 layers nearest to it, contain more water than the outer 

 ones, i. e. if they are softer and less consolidated than the 

 outer layers, we might assume with tolerable certainty 

 that the central layers which surround the nucleus are the 

 youngest, and the peripheral ones the oldest. Now, if 

 this hypothesis be retained as the most probable, there is 

 no difficulty in explaining the spot where the nucleus 

 should be found. Accordingly as the layers happen to 

 be thick or thin, the nucleus must be situated more or less 

 excentrically, in fact it must be excentric in the large 

 globules. For as soon as the centripetal formation of 

 the layers was uniform in all parts of the inner surface, a 

 condition would occur, which would prevent any further 

 development, because the walls being everywhere of equal 

 thickness, the transmission of new nutritive matter would 

 be prevented, whilst this condition would never occur if one 

 part of the granule were thinner than the rest. When 

 the walls of the cells are thicker, other means come into 

 play in facilitating the access of nutriment, viz. pore- 

 canals. The author moreover adds : " We must rest 

 satisfied for the present, with the conclusion which has 

 been arrived at negatively, that a process similar to that 

 of cell-formation must be admitted to occur in the case 

 of the granules of starch, the nature of which must form 

 an object of future investigation." It is very pleasing to 

 find that the author has differed from the ordinary ex- 

 planations of the formation of starch. I quite agree in 

 his opinion, that the granules of starch are formed from 



