326 M. H. V. Mohl on the Structure of Chlorophyll. 



colourless coat completely distinct from the contents and ex- 

 hibiting a double outline ; such an appearance is never found 

 anywhere in nature. 



The alteration of the chlorophyll-granules in water, in which 

 their membrane is said to present itself so distinctly, will be 

 spoken of more particularly further on, when it will be shown 

 that phsenomena occur here, deviating essentially from the de- 

 scriptions of former observers. 



With regard to the second point of Nageli^s theory, the agree- 

 ment of the hardened surface of the granules with the pri- 

 mordial utricle of the cell, this comparison is devoid of any solid 

 foundation. The cases in which the primordial utricle can be 

 observed in the fresh cell, without application of alcohol, acids, 

 iodine, &c., and without its appeai-ance being obscured by the 

 rest of the contents of the cell, are anything but frequent. In 

 such cases, for instance in Zijgnema and Cladophora, it presents 

 itself as a special layer composed of a linely granular substance, 

 not coalescing w^ith the remaining contents of the cell, defined 

 equally against the cavity of the cell and on the outside, with 

 w^hich layer the structures composed of proteine-compounds, the 

 circulation currents, and the layer containing the chlorophyll, 

 are indeed in contact, but from which they are sharply sepa- 

 rated. In an anatomical point of view, in the occurrence as an 

 independent layer, therefore, there is an essential distinction 

 between the primordial utricle and the outer consolidated sur- 

 face of the chlorophyll-granules, &c. That we cannot everywhere 

 observe the pi-imordial utricle as an independent layer is cor- 

 rect, but it would be a mistaken course to set out from indistinct 

 observations and build a theory upon these. Unless we would 

 open the door to unbridled fancy, we must take our stand upon 

 cases in which the conditions can be observed in the simplest 

 details, and these speak for the separation of the primordial 

 utricle, as an independent layer, from the remainder of the cell- 

 contents. 



Farther, no parallel can be drawn, in a physiological point of 

 ^dew, between the primordial utricle and the more solid outer 

 layer of the nucleus, chlorophyll-granules, &c. On the outside 

 of the primordial utricle, and, we have ground to assume, in 

 consequence of its action, cellulose membi'anes are formed ; on 

 the outside of the chlorophyll-granules, &c., this never takes 

 place. From this difference of function we must deduce a dif- 

 ference of the organs. As relates to the chemical character of 

 the primordial utricle, we still know very little about this. That 

 it is coloured yellow by iodine, and hardened by the action of 

 alcohol and acids, is by no means any proof that it is nothing 

 but a layer of proteine-substance ; its elements may have an 



