i8j. Neiv Botanical Books. 



of plant structure.' The intention is excellent, but the performance very 

 disappointing. One looks for life histories, and finds, for the most part, 

 scraps of information interwoven with very crude ideas on evolution. 

 Frequent errors occur in elementary details, and little care is exercised 

 as to choice of terms. He speaks of the sycamore fruit constantly as the 

 seed,' and explains how the ' seeds ' should have developed wings, 

 etc. Of the root-cap he says, ' within this is the true growing tip of the 

 root, but it is the sensitive root-cap which guides the root tip to suitable 

 quarters.' According to the author, the thorns of the Gorse arise thus : 

 ' higher up the stem the leaflets get thinner and sharper, gradually changing 

 into thorns.' Plate XLVII. contains excellent figures of Cacti, but, 

 instead of pointing out the importance of the radiating spines in function- 

 ing as a light screen, he says ' they obviously run no risk of getting their 

 leaves scorched by the hot rays of the sun,' overlooking the advantage of 

 protecting the green tissue of the stem. These are only a few of many 

 similar statements the book contains, and we agree with the author when 

 he says, on p. 95, ' It is true that the science of Botany may be pursued by 

 different methods from those I have adopted in this chapter,' and we 

 can only hope it will be. 



The Heridity of Acquired Characters in Plants, by the Rev. Prof. 

 G. Henslow, M.A., F.L.S. John Murray, pp. XII. and 107, with 24 

 illustrations. 1908, price 6/- net. 



The author declares that the object of this book ' is to prove that 

 Evolution — so far as plants are concerned — depends upon the inheritance 

 of acquired characters,' in opposition to Wiesmann's view that such char- 

 acters are not transmitted unless the influence of the environment reaches 

 the reproductive cells. In this matter Prof. Henslow has set himself a 

 very difficult task, and in reading carefully over his pages, we are by no 

 nieans certain that his attempt has been successful. He declares with 

 great emphasis that present-day ecologists are all at one in accepting the 

 view he advocates, but he adduces very little evidence of this, and we look 

 in vain for definite experimental proofs brought forward by the ecologists 

 he claims as supporters. He says, ' Germany, France, Denmark, the 

 United States, South Africa abound with ecologists .... but, as Darwin 

 himself was the first to profound [sic] this view, I called it " The True 

 Darwinism." ' Many general observations have been made, and a certain 

 amount of detailed work has been done on the effect of environment on 

 plant form and structure, but examples are exceedingly rare where such 

 modifications are shewn to give rise to new species. Such acquired 

 variations usually persist only so long as the conditions of the environment 

 which called them into being, persist ; that is, they are continuous varia- 

 tions but that continuous variations are inherited has not been by any 

 means generally proved, nor is it an easy task. 



Another difficulty in dealing with continuous variations is to distin- 

 guish those which are genetic from those which are acquired, and in many 

 of the illustrations given in this work, no attempt is made to deal with these 

 distinctions. Cases like the water-buttercup furnish pretty good examples 

 of the inheritance of acquired characters, but they are so rare that, in 

 spite of the author's many assertions, we still await more such proofs be ©re 

 we can declare with confidence either that ' all structures arise by direct 

 adaptation by response,' or that such acquired characters play an impor- 

 tant part in the evolution of species. However, Prof. Henslow brings 

 forward many facts which of themselves, are valuable and interesting 

 and if the book induces workers, even ecologists, to pay attention to the 

 matter and furnish a quality of evidence at all comparable to that of the 

 Mendelians, it will have served a very useful purpose. ^^_^ 



P Messrs. Cassell & Co. are unquestionably doing excellent service by 

 placing before the public popular botanical works at so very low a price. 

 They are just issuing three excellent publications, all of which will doubtless 

 find a ready sale amongst the increasing number of nature students. 



NaturalistI 



