138 



SCIENCE 



[N. S. Vol. XXXrV. No. 866 



lowed by subsequent investigators in 

 working out life histories of other forms, 

 and there is no doubt now that the proto- 

 zoon life cycle involves more or less definite 

 asexual and sexual periods. In parasitic 

 protozoa the sexual phase, including ma- 

 turation, conjugation and fertilization, 

 undoubtedly leads to renewed vigor of the 

 race, or to a new power of asexual devel- 

 opment, and to this extent at least, the 

 time honored view of Biitschli's (1876) 

 that conjugation is a means of the "Ver- 

 jungung" or rejuvenation of the cell,- is 

 warranted. 



Associated with these alternate phases 

 in the life history are the remarkable 

 changes which accompany development of 

 the sexual phase. These, involving the 

 problems of sex, are particularly impor- 

 tant in connection with the nuclear 

 changes whereby a specific germinal 

 chromatin is formed, sometimes at an early 

 stage, in the asexual phase, and persisting 

 as a germ plasm until used in the forma- 

 tion of gamete nuclei. 



I have now given enough of the scope of 

 protozoology to indicate that the proto- 

 zoologist, far from being a strict specialist, 

 rather immodestly claims the greater part 

 of the whole field of biology as his own, 

 and I would define protozoology, therefore, 

 as that branch of the biological sciences 

 which deals with the application of biolog- 

 ical problems to, and with search for their 

 solution in, the lowest group of animal or- 

 ganisms — the Protozoa. 



Gaky N. Calkins 



SYNTHETIG METALS FROM NON-METALLIC 

 ELEMENTS i 

 It is one of the most striking facts of 

 chemistry that three fourths of all the ele- 

 ments are metals. But it is no less re- 



' Eead at the meeting of the American Chemical 

 Society, Minneapolis, December, 1910. 



markable that metallic properties are con- 

 fined exclusively to elements in the free 

 state or, in case of alloys, to combinations- 

 of typically metallic elements. 



In recent years the theory of the nature 

 of the metallic state has been steadily de- 

 veloping into more and more precise form, 

 so that to-day we have, in the electron the- 

 ory of matter, a very satisfactory explana- 

 tion for all of the characteristic properties 

 of metals. Inasmuch as it is just a cen- 

 tury since Davy proposed his celebrated 

 metallic ammonium theory, we may now 

 well consider whether metallic properties 

 are, of necessity, confined to elements in 

 the free state. 



During the last two decades a vast 

 amount of experimental evidence has been 

 accumulating that electricity is granular 

 in structure, though such a conclusion was 

 strongly indicated three quarters of a cen- 

 tury ago by Faraday's discovery of the 

 facts epitomized in the law of electro-chem- 

 ical equivalents as first pointed out by 

 Helmholtz in 1881. The granules or ulti- 

 mate atoms of electricity are now called 

 corpuscles or electrons. The charge of 

 the electron is negative in sign. In fact 

 we have decisive experimental evidence of 

 only this one kind of free electricity, posi- 

 tive electrification of a body, being from 

 this standpoint merely a deficiency of elec- 

 trons. 



J. J. Thomson has shown how from the 

 conception of an atom made up of electrons 

 rotating in a sphere of positive electrifica- 

 tion, there follows a simple explanation of 

 many of the properties of an atom, in- 

 cluding valence ; a univalent atom, if nega- 

 tive, being one that can gain an electron, 

 if positive, one that can lose an electron. 

 A bivalent can gain or lose two electrons. 

 A trivalent atom, three, etc. According 

 to this hypothesis the most fundamental 

 property of an atom of an element is this 



