338 Theory of Cell-formation [BOOK n. 



' Die Pflanzenzelle,' published in 1852, a book which claimed 

 to expound all parts of phytotomy by the aid of the author's 

 own observations, with occasional reference only to the 

 writings of others ; the attempt was so far impossible, as 

 the essential points had already been fully cleared up by 

 the labours of other botanists. The work had however the 

 advantage of attracting the attention of the reader by nume- 

 rous good original drawings, and the style was enlivened 

 by the constant appeal to original observation ; at the same 

 time, through insufficient use of the available literature, the 

 author's views not unfrequently fell short of the existing 

 standard of knowledge. Worse than this however was a 

 certain defect of education, which led the writer into self- 

 contradiction and to incorrect classification of his facts ; things 

 fundamentally important were sometimes neglected for un- 

 important details, and a certain unreflecting empiricism was 

 apparent in the whole work, in marked contrast with the 

 logical exactness of von Mohl, Nageli, and Hofmeister. In 

 the second edition of the work, published in 1856 under the 

 title, ' Lehrbuch der Anatomic und Physiologic der Gewachse,' 

 we find many improvements in the details, but still on the whole 

 the same formal defects. It is not unimportant in a historical 

 point of view to notice this character of Schacht's writings, be- 

 cause during this period most young botanists and other persons 

 also derived their knowledge of phytotomy and of the nature 

 of cells chiefly from him ; his books did not truly represent the 

 condition of the science ; their defective reasoning had an 

 injurious effect on the minds of younger readers, and they intro- 

 duced into phytotomy and vegetable physiology a habit of ac- 

 cumulating a mass of undigested facts, such as has for some time 

 marked the condition of morphology and systematic botany. 



Unger's text-book ' Anatomic und Physiologic der Pflanzen ' 

 (1855) was superior in conception and execution. It intro- 

 duced the beginner to the doctrine of cells with careful 

 attention to all that was known on the subject, if sometimes 



