414 REVIEWS. 



fluence of the surrounding medium, and grows rapidly, and 

 the colourless protoplasm within shows streams laden with 

 " microsomes ^' playing exactly as at the incipient cross- 

 septum during the division of the cells, and hurrying to- 

 wards the terminal inner surface, there to become arranged 

 into a sheet which forms a new lamella. This peculiar, 

 microsome-ladeu sheet was earlier described by Strasburger 

 as a condition of the outer portions of the protoplasmic 

 body (Hautschicht), in which rod-like elements appear. 

 Fine, hitherto not understood protuberances now seen 

 inside the cell-wall, are explained as already consolidated 

 portions of the layer. As the thickening thus occurs, 

 the caps formed over the growing end are stretched by 

 pressure, and the lamellse become closely and tightly fused 

 together. 



A short section on the formation of membranes in the 

 animal kingdom follows, and need not here be further 

 noticed ; it is of interest, however, to observe how com- 

 parisons between the two kingdoms can be instituted in this 

 connection. 



From this point onwards, the last one fifth of the book 

 is occupied with almost purely hypothetical considerations, 

 and is in most respects decidedly less valuable to the mor- 

 phological student ; nevertheless, the crystallisation of the 

 numerous ideas around the nuclei of facts obtained gives us 

 a clear insight into the peculiar sphere of thought in which 

 Professor Strasburger moves and works. Nor do we pre- 

 sume to question the propriety of such speculations as are 

 here brought forward, especially on the ground which the 

 author appears to take up, viz. that even where his speculations 

 are of little permanent value they serve to direct attention 

 to the points in question. Professor Strasburger undoubt- 

 edly shines more as an observer than as a theorist, however, 

 and we cannot sympathise with him in many of his fine 

 distinctions in this part of the book, e.g. the proposal to 

 limit Naegeli's term " Micella," and the discussion as 

 to the mode of increase of " microsomes," " Starke- 

 bildner," &c. 



We shall content ourselves with referring the reader to 

 the book itself for the author's view on the " double refrac- 

 tion of organised structures," and on the " molecular struc- 

 ture of organised bodies,'' merely stating that he believes 

 the phenomena of refraction by which Naegeli supports the 

 intussusception hypothesis, can be equally well explained 

 without assuming the presence of the Micellae, as defined 

 by Naegeli, as the effects of tension, &c. 



