ANNOTATIONS. 



Page 4. — ^Without engaging in controversy, rather to 

 show our high esteem for Kiitzing, we deem it necessary 

 to subjoin a few words, lest we should seem desirous of 

 eluding the question, or not duly weighing the reasons of 

 this excellent author. " There do not exist in nature 

 definite {sckarfe) boundaries between species, classes, and 

 kingdoms, and our having admitted these theoretically, 

 leads us to regard some inferior animal forms as plants, 

 and some vegetable forms as animals. The limiting of 

 the boundaries between the two organic kingdoms is 

 always a problem. All metaphysics should be excluded 

 from the study of nature, in which we can only proceed 

 by the empirical way, and therefore we ought to restrict 

 ourselves to what we see, observe, and understand." 

 These thoughts, expressed by Kiitzing, (' Ueber die 

 Verwandlung der Infusorien in niedere Algenformen ' 

 Preface,) are strictly logical. But the conclusion deduced 

 by the author is not legitimate, that we ought to admit a 

 common point of departure for the two kingdoms. If it 

 be absurd to admit the problem to be solved positively, it 

 is equally so to admit that it is decided negatively. The 

 contradictions to which he alludes, as produced by the 

 false supposition of the existence of a limit between the 

 two kingdoms, belong to authors or books, and not to the 

 science. The very examples, the mhraiile cilice of Surirella 

 Gemma (Ehrenberg), and of the spores of Vaucheria 

 clavata (Unger), have an answer in the observation of 

 Siebold. All the observations on the mobility of the 

 sporidia of the inferior Algse, of the spores of Vaucheria, 



