90 NOTICES OF BOOK3. 



Dr. Hoffmann then proceeds to determine the absolute value of 

 meteorological conditions upon the growth of plants, in the following 

 manner : taking the leafing of Amygdalus Persica as an example, its 

 leaves grew rapidly at first, and reached a maximum rate of growth 

 (six lines) on the 21st of April, increasing as the power and warmth 

 of the sun increased, and the consequently warmer days and nights. 

 On the 22nd, the rate of growth had decreased rapidly, in consequence 

 of the weakened power of the sun's rays on this and the preceding 

 days, in spite of the higher maximum and milder nights. From thence 

 to the 24th, contemporaneously with rthe rapid sinking of the tempera- 

 ture of the earth, accompanied with frosty nights, the growth further 

 decreased, in spite of the long sunshine. After rain, with the cooler 

 mean temperature and lower maximum, the growth diminished, and 

 ceased altogether on the 30th of April. 



The value of such observations as these does not depend upon the 

 nicety with which the growing organs are measured to minute fractions 

 of inches, but upon the number of observations from which the mean 

 results are reduced ; and it is satisfactory to find that Dr. Hoffmann 

 has not confined his observations to single specimens and species, nor 

 to plants sown at one season of the year only. On the other hand, it 

 appears to us that equally useful results might have been attained at 

 infinitely less expenditure of time and labour, and it is not without 

 wonder that we find no allusion throughout the whole book to M. De 

 Candolle's ' Geographie Botanique Kaisonnee.' The latter work, whe- 

 ther -for the number and value of the results of similar observations 

 that it offers, or for its analyses of the methods of obtaining such re- 

 sults, appears to us of essential use in all such investigations, whilst to 

 ignore its existence and that of M. JDe Candolle's previous researches, 

 is simply incomprehensible. 



The considerations to which the remainder of the work is devoted 

 do not strike us as either original or suggestive, with the exception of 

 some observations and experiments upon the process of freezing in 

 leaves ; but the whole is enveloped in a cloud of verbiage that renders 

 any attempt to sift what may be new or important from the rest, a far 

 from promising operation. A summary of the author's results would 

 have been a boon, or rather might fairly be demanded by the reader, 

 who must else wade through nearly six hundred pages of very unat- 

 tractive matter in the attempt to obtain it for himself. 



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