1890.] Recent Literature. 259 
Here the changes are fewer. The antiquated term ‘‘ spongiole’’ is 
still preserved (p. 257), though for what purpose is not clear. The 
root-cap, immediately following, is not properly described. On page 
310 we still find the statement that about 100,000 stomata ,‘‘may be 
counted on an average-sized apple leaf,” when, as a matter of fact, it 
has been known that there are more than that many on each square 
inch. Morren’s figures are 246 per square millimeter (Pringheim’s 
Jahrbiichen fiir wissens. Botanik, Vol. IV., p. 190), and these are 
equivalent to 158,670 per square inch. 
The paragraphs on fertilization and hybridization have been entirely 
rewritten, while that on species has undergone a significant change. 
Twenty years ago our author wrote the original pamphlet in such away 
as to involve “‘ original and permanent differences between different 
species.” Then he cautiously admitted a short paragraph about 
“ Darwin’s Hypothesis,” which he said ‘‘is now accepted by many 
naturalists ;’’ but he says further, in a deprecatory tone, ‘‘ our object 
here is not to discuss this intricate question,’’ etc., etc. In comparing 
these cautious, not to say timid, references in the first edition to the 
modern idea of the evolution of species, with the treatment of the 
subject in the new book, one is able to realize the progress we have 
made in the last score of years. Now the old doctrine is spoken of in 
the past tense / ‘‘ Such supposed original kinds were called species’’ 
(p, 325). A little further on, in referring to the present view, we find 
this: “On this view a plant species comprises a number of indi- 
viduals, among which we are unable to distinguish greater differences 
than experience shows us we should find among a number of plants 
raised from the seed of the same parent.’’ A very good definition of 
a species is this. CHARLES E. BEsseEy. 
New Hand-Books of Paleontology.*—The rapid development 
of the science of Paleontology in recent years, has been naturally 
followed by the production of text-books which are designed to bring 
the subject within reach of students and readers. The three works 
here referred to have the advantage over many similar publications 
of being the production of experts in the science, and not of mere 
3 Elemente des Paleontologie von Steinmann und Döderlein ; Strassburg, 1890, 8vo, 
. 829. 
Handbuch des Paleontologie, herausg. von Prof. K. A. von Zittel mit Wirkung 
von Dr. A. Schenk. 1. Abth., Paleozodlogie. III. Band; 3 Lief. Reptilen, rst part, 
PP. 437-632, 1889. 
Manual of Paleontology jer the use of Students ; by R. A. Nicholson and R. Lydek- 
ker; 2 vols., 8vo., pp. 1654; William Blackwood & Sons, Edinburgh and London, 1889. 
