1889- J BOTANICAL GAZETTE. 6 1 



■ 



tions and permutations all living and extinct organized crea- 

 tures. 



It is a curious fact that Darwin himself has not laid much 

 stress on the peculiarity of his gemmules as not representing 

 each the whole organism, but only a single or a few hered- 

 itary characters. But he thought that this proposition was 

 evident to all those who had studied the subject. He even 

 thought, for a time, that his views were materially the same 



with those of Spencer, who wrote some years before him, al- 

 though he afterwards saw that this was not the case. 



Perhaps to this circumstance, also, it may be partly at- 

 tributed that the hypothesis of pangenesis has as yet found 

 few adherents among leading naturalists. But now this ob- 

 stacle has been removed. The name of gemmules, which 

 caused so many misunderstandings, is replaced by another. 

 Last, but not least, Prof, de Vries has clearly shown that on 

 no other known assumption can many important classes of 

 facts be connected together so well as on that which forms 

 the basis of pangenesis. I have no doubt that for this hy- 

 pothesis a new era begins with the publication of this book. 



In the second part of his book the author deals with the 

 more recent discoveries in cellular morphology. He shows 

 that the hypothesis of pangenesis, as set forth in the first 

 part, is in perfect accordance with what has been brought to 

 light for the most part long after Darwin had written his hy- 

 pothesis. It is only natural that in applying it to the micro- 

 scopical structure of cells some questions arise. These have 

 been answered by the author, and thus some additional 

 propositions are made, which, together with the original 

 hvpothesis, constitute what the author has called ''intracel- 

 lular pangenesis." 



This second part of the book is much longer than the 

 first, but it is impossible, in so short a compass as is allowed 

 here, to mention many details, which are, however, necessary 

 for fairly reproducing it. I must be content with giving only 

 some faint outlines, which perhaps will induce the reader to 



peruse the book itself. 



In the first place, it must be remembered that Prof, de 

 Vries, in one of his former publications, 4 has explained his 

 views on the structure of the protoplasmic body of vegeta- 

 ble cells. With Hanstein, he considers the protoplasmic 



conte 



he gi 



ents of every cell as an individual, and, with this author, 

 ives to it the name of " protoplast/' He is opposed to 



* Plasraolytische Studien. Pringsh. Jahrb. xvi. p. 489. 



