150 SOME NEW BOOKS [aAucust 1899 
Bilder, by Hélzel of Vienna, the forestry maps of Sargent, showing the distri- 
bution of trees in North America, and many other items of importance which 
suggest, like the journal itself, the great progress at present being made in the 
science and teaching of geography. 
In Science of June 23 Prof. R. W. Wood describes his diffraction process 
of colour-photography, which is really a variation of the three-colour method ; 
and Prof. E. Thorndike discusses the mental fatigue of school work, furnishing 
additional data which render more probable his previous conclusion that 
“the mental work of the school day does not” [at the time] ‘“ produce any de- 
crease in the ability to do mental work.” 
The eye of the Amphipod Crustacean 4blis serrata receives attention at 
the hands of Dr. 8. D. Judd in the May issue of the Proc. Biol. Soc. Wash- 
ington, and is found to be remarkably different from the corresponding organ 
of Gammarus. It appears to be a compound eye constructed on the general 
plan of an ocellus, but furnished with a space which may be the functional 
representative of the space occupied by the vitreous humour in the vertebrate 
eye. Further investigations are, however, needed before the full significance 
of all parts of this organ can be determined. 
The Alaskan Moose, or Elk, has long been known to be the largest representa- 
tive of its kind, and it appears to be mainly on this feature that Mr. G. 8. 
Miller relies in describing it as a new species (Alces gigas) in the recent issue 
of the serial last quoted. Most English writers regard all the living repre- 
sentatives of the Elk as referable to a single wide-spread species. In recognis- 
ing three specific forms in what is essentially one and the same animal, Mr. 
Miller shows the value to be attached to species recently named by American 
writers among the smaller Mammals. 
Prof. Weismann’s essay on regeneration appeared contemporaneously in 
Natural Science (in English) and in the Anatomischer Anzeiger (in German). 
A reprint of the German edition has been published in pamphlet form by Mr. 
Fischer of Jena, to whom we are indebted for a copy. It is entitled ‘ Thatsachen 
und Auslegungen in Bezug auf Regeneration,” occupies 31 pages, and costs 60 
pfennigs. 
