THE AMERICAN NATURALIST [Vol. XLT 



Montgomery states that two species are as distinct in the egg-cell stage 

 as in any later one, "no matter whether the differences are as percepti- 

 ble or not."^ Such a statement, however, evades the question whether 

 or not embryos of related species can actually be distinguished from 



The four suborders of rodents, represented by the squiriel, mouse, 

 guinea pig, and rabbit respectively, according to Lee may be distin- 

 guished at very early stages. His studies do not enable him as yet to 

 recognize the genera of one suborder, — namely the gophers, prairie 

 dogs, squirrels, and cliijimunks — until the embryos are far advanced. 

 Differences in tunicate eggs of closely related genera have, hoAvever, 

 been recorded by Conklin, and ^McClung can distinguish several 

 species in one genus of grasshojjpers by the chromosomes of their 

 germ cells. 



F. T. L. 



ZOOLOGY 



New Text Books of Zoology.— The most iiiii)(>rtaiu service thiit 

 biology can render to students is to train their rcaxm and ilicir power 

 of observation, and to free them from a too dccj) rcvcn-iice for authority. 

 This service can also be p('rforine<l l)y tlie other natural .sciences, 

 physics and chemistry, which an- coniiiionly nichidcd in the cnrricuhi 

 of high schools but which rccitiire expensive apparatus Ix-yond the 

 reach of many schools. Biology, however, can be profital)ly taught 

 with so slight an equipment that every school can aflonl to underiak(> 

 to teach botany or zoology, or both. The teaching- of biolouy lias 

 often failed to yield the results that educators liave expecte.l. This 

 is so because teachers too often yield to the temptation to tell ilie 

 students the facts and theories which they ought to learn by their o\\ n 

 efforts, instead of teaching them how to discover, to class ity, and to 

 draw proper conclusions. 



Professor Gletm W. Ib-rrick. of the Mississippi Agricultural College 

 has endeavored to meet tlie needs of the high school of limit. -d means 

 whose students will, as a whole, have no further instruction in bioh.^^v. 



