ABSTRACTS 



Authors of scientific papers are requested to see that abstracts, preferably 

 prepared and signed by themselves, are forwarded promptly to the editors. 

 The abstracts should conform in length and general style to those appearing in 

 this issue. 



INORGANIC CHEMISTRY.— A^ote on the sintering of magnesia. 

 John B. Ferguson. Journ. Amer. Ceram. Soc. 1: 439-440. 

 June, 1918. 



The sintering of chemically pure magnesia has been generally re- 

 garded as difficult if not impossible, and this note is intended to place 

 upon record the conditions under which such a sintering was found 

 to take place readily. Pure magnesia powder, upon prolonged heating 

 at temperatures ranging from 1600° to 1720° C, sinters to a cake of 

 considerable mechanical strength and this sintering is due to a recrystal- 

 lization, forming a mass of interwoven crystals, rather than to the 

 presence of any bonding materials. J. B. F. 



ENTOMOIyOGY. — Origin oj the castes of the common termite, Leuco- 

 termes flavipes Kol. C. B. Thompson. Journ. Morph. 30: No. 

 I. 1917. 



Termites, since they belong to that most interesting group known 

 as "social insects," have been studied with interest by entomologists 

 for many years. One of the most important unsolved problems in the 

 complex life cycle of termites has been the origin of the castes. 



There have been two theories as to the origin of the castes. According 

 to most of the older writers, all the young are undifferentiated or alike 

 upon hatching, and only become differentiated later through the ex- 

 ternal influences of food or protozoan parasites; the other view is that 

 the castes are predetermined in the egg or embryo by intrinsic factors. 



Dr. Thompson shows that the fertile and sterile types are prede- 

 termined at the time of hatching and may be distinguished by the 

 bulk of the brain, the relative size of brain and head, the structure 

 of the compound eyes, and the size of the sex organs. He also proposes 

 a simplification in the nomenclature of forms and castes in termites 

 and in this and a previous paper on the origin of the frontal gland 

 in termites. T. E- SnydER. 



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