238 



SCIENCE. 



[N. S. Vol. IV. No. 86. 



Lowell's misconception of the mathematical 

 principles of the ' great circle ' is fundamental. 

 Does it render null and void his conclusion that 

 the canals lie on arcs of great circles ? 



Mr. Lowell found that the surface markings 

 on Mars came to the central meridian about 

 twenty minutes later than the predicted time; 

 a discrepancy, it should be said, to which Prof. 

 Keeler called special attention in 1892. 



To what extent Mr. Lowell's future observa- 

 tions will modify his map is uncertain. Draw- 

 ings of Mars by different observers even on the 

 same night and with the same telescope are 

 proverbially different. So far as the drawings by 

 the three Flagstaff observers have been pub- 

 lished, the proverb still seems to be in force. 



Mr. Lowell is entitled to great credit for de- 

 voting his private means so generously to es- 

 tablishing and conducting an observatory, and 

 for his efforts in search of the best, but imper- 

 fect, atmospheric conditions. He is likewise 

 fully aware of the necessity of making the ob- 

 servations continuously and systematically. 

 Whatever advances Mr. Lowell may have made 

 in Martian study, or may make in the future, 

 will be fully accredited to him and warmly 

 welcomed by all astronomers. 



Mr. Lowell's book is written in a lively and 

 entertaining style, and is printed and illustrated 

 faultlessly. It is true that the theories ad- 

 vanced are mostly old ones, suggested by Schi- 

 aparelli, Pickering and others, many of them 

 having been elaborated by Flammarion and 

 others; but Mr. Lowell has presented them 

 very fully and suggestively. Scientifically, the 

 leading faults of the book are: First, that so ■ 

 elaborate an argument for intelligent life on the 

 planet, embracing a complex system of seasonal 

 changes, should be based upon observations 

 covering only one-fourth of only one Martian 

 year; and, secondly, that there should be so 

 many evidences of apparent lack of familiarity 

 with the literature of the subject. 



W. W. Campbell. 

 Lick Observatory, 



University of California. 



Text-book of the Embryology of Invertebrates. By 

 Dr. E. Korschelt and Dr. K. Heider. 

 Translated from the German by Edward 



L. Mark, Ph. D. , and W. Mc. "Woodworth, 

 Ph. D., with additions by the authors and 

 translators. Part I. : Porifera, Cnidaria, 

 Ctenophora, Vermes, Enteropneusta, Echi- 

 nodermata. New York: Macmillan & Co. 

 8vo. Pp. xv+484. 1895. $4.00. 

 The first Heft of the special part of Korschelt 

 and Heider' s well-known Lehrbuch, of which 

 this is the English translation, appeared in 1890; 

 the second Heft appeared in 1892 and the third 

 in 1893. The three parts together form a vol- 

 ume of some fifteen hundred pages, illustrated 

 by some nine hundred figures. They complete 

 the special part of the work, that which pre- 

 sents the facts of embryology. A general part, 

 to deal with theories and conclusions, is prom- 

 ised. 



The first volume of Balfour's Comparative 

 Embryology, dealing with invertebrates, ap- 

 peared in 1890, and following that, the work of 

 Korschelt and Heider was the first attempt at a 

 ' broad and comprehensive ' treatment of the 

 whole field of invertebrate embryology. The 

 book has been for several years in the hands of 

 zoologists all over the world and is recognized 

 as an excellent and indispensable reference 

 book, the only one of its kind since Balfour. 

 The labor involved in reading the special pa- 

 pers dealing with each group of animals treated 

 and in sifting and arranging their results is so 

 enormous, and the work of Korschelt and Hei- 

 der has been so well done, that the book is 

 likely for many years to remain without a> 

 rival. It is too well known to need critical 

 treatment in this place. 



The translation under consideration covers 

 the first three hundred and twenty pages of the 

 original. The remaining four-fifths of the book 

 is to be rendered by another translator. 



The German has been more freely rendered 

 than in Mark's translation of Hertwig's Text- 

 book of Embryology, and this gives the present 

 book better literary form and makes it easier 

 reading. At the same time the original has- 

 been so closely followed that nothing is lost oi 

 its meaning. The few instances where the 

 English is not perfectly clear are not likely to 

 confuse anyone who is prepared to read the 

 book. Here are some of them: On p. 17 ' dif- 

 ferenten ' is rendered by differentiated, which 



