Reviews and Book Notices. 



311 



controlled mainly by the temperature of the water, the flowering 

 plant vegetation and the character of the bottom of the pond 

 are not unimportant factors. The changes of temperature 

 during the course of the year induce in the same pond a striking 

 succession of associations. The following algal associations, 

 named according to the dominant form, will be treated in detail 

 in a subsequent paper : — 



Winter. — i. QEdogonium. 2. Tribonema. 



Summer. — 3. Mougeotia. 4. Spirogyra. 5. Tolypothrix. 



6. Anabaena. 7. Phormidium. 8. Microcystis. 



Nature Study.: an Eas}' Key to the British Cruciferous Plants.* By 

 William Ingham, B.A. (Lond.). 



That an artificial key to the cruciferous species of plants should be 

 labelled Nature Study seems to us somewhat inappropriate, to say the 

 least ; and whether Air. Ingham's little school-book is really a desideratum 

 for 3'oung- nature students is very doubtful. It is certainly not necessary to 

 the older botanist, who is already well supplied with fuller and more explicit 

 keys in many standard works. Notwithstanding- the good descriptions of 

 the species and the explanations of the Latin and other terms — rather 

 a matter for the word-student, however, than the nature student — we fear 

 the whole will act as a deterrent rather than an inducement to the end in 

 view. The question of determination of the leading naitural orders of 

 plants is not so difficult a matter ; but it is far more important to the young 

 student than the discovery of genus or species. The little brochure would 

 set youthful scholars on to work that is always relegated to the expert. 

 Let alone the extreme difficulty of defining 'species' and 'genus," there is 

 the fact that at least seven of the genera and about thirty of the British 

 species are exceeding-Iy uncommon plants. Our friend would make pupils 

 of a tender age specialise with a vengeance, and that not on the hig-hest 

 form of botanical science. 



Mr. Ingham describes in homely English terms when possible, and that 

 is a g-ood point ; but that there is plenty of opportunity for extending the 

 classical vocabulary one need only notice the nomenclature of the genera 

 and species in his list. 



Of the diagTams, which, of course, mean well, one cannot speak very 

 highly in the matter of their accuracy or lucidity. Why should ' C ' in 

 Fig. I appear so like an inferior ovary rather than a cruciferous calyx 

 of four sepals? Surely a good half side view of wallflower or cuckoo- 

 flower would show the sepals distinctly. Fig. 2 is altogether misleading. 

 Each pair of stamens (vide under 'B') should appear opposite and not in 

 the sanie plane ; and this could have been made clear enough in a half side 

 view or semi-perspective elevation. The seeds on the replum in Fig. 3 are 

 apparently fixed like those of no crucifer in existence. They should not 

 appear opposite to, but alternate with one another. And why the siliqua 

 in Fig. 26 should be inverted one cannot very well see. Cruciferous fruits 

 rarely de-pend. 



The last sentence in the book will, doubtless, evoke feeling's of the 

 mysterious, i.e., the germination of seed after the conflagration of a town, 

 and the old fallacies of mummy wheat, charlock after long fallow or long rest 

 from cultivation, white clover after 'liming' or marling, et hoc genus omne. 



The price of the booklet, sixpence, seems to us quite plenty, w'hen it is 

 rem-^mbered that one can get the fullest keys to all the genera and species 

 of British flora, together with the descriptions thereof, for a few shillini;s. 



* A. Brown & Sons, Hull. 6d. 



1905 October 2. 



