a vigorous and trenchant criticism of Haeckel's Gastrula the- 

 ory, exposing its weak points. Mr. Agassiz regards the assump- 

 tions of Haeckel forming the basis of his Gastrula theory as 

 "wholly unsupported." It must "take its place by the side of 

 other physio-philosophical systems," and he denies that we have 

 been " able to trace a mechanical cause for the genetic connection 

 of the various branches of the animal kingdom." 



Entomology in Illinois. 1 — We have noticed previously the im- 

 portant entomological reports made by Mr. Riley to the state of 

 Missouri ; we now have before us a Report of about two hundred 

 pages by the state entomologist of Illinois. It is fully illustrated 

 by admirable drawings mostly from the pencil of Mr. Riley, and 

 is well printed. Instead of treating directly of injurious insects, it 

 is a treatise on the beetles of the United States, and as such will 

 serve to prepare the way for future reports on economic ento- 

 mology. The work is excellent as an introduction to a study of 

 the beetles, which comprises some of the most injurious species, 

 and we bespeak for it a large circulation outside of the state. We 



but the aim of the work and successful treatment of the subject 

 new beetles are described and figured. 



Polarization of Light. 2 — This is another of the elegant and 



" Nature." They contain the substance of lectures delivered at 

 various times to workpeople, and " constitute a talk rather than a 

 treatise on polarized light," says the author. 



BOTANY. 



Gray discusses this question, and concludes that " sexually propa- 

 gated varieties, or races, although liable to disappear through 

 change, need not be expected to wear out, and there is no proof 

 that they do ; also, that non-scxually pn^a^itrd varieties, though 



