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2 SCIENCE-ADVERTISEMENTS VoL. 93, No.2412

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2 SCIENCE-ADVERTISEMENTS VOL. 93, No. 2412

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I4 SCIENCE-ADVERTISEMENTS VoL. 93, No. 2412

SCIENCE

VOL. 93 FRIDAY, MARCH 21, 1941 No. 2412

Evolution of the Germ-Plasm: PRoFESsoR C. E. MC- Special Articles:CLUNG .. ................ 265 Chemistry of Energetic Atoms Produced by Neu-

tron Capture: PROFESSOR W. F. LIBBY. TheThe Zoological Society in These Times: FAIRFIELD Effect of Heat on Crystals of Serum Albumin;OSBORN .... ........ 269 Production of Crystals of Denatured Protein: DR.

- A. E. MIRSKY. N1-(f-Aminoethyl)SulfanilamideObituary: and N'-(f3-Diethylaminoethyl)Sulfanilamide: PRO-Dayton Clarence Miller: PROFESSOR H. W. MOUNT- PESSOR LAWRENCE H. AMUNDSEN and LENA A.

CASTLE .2 M.8........................MALENTACCH

Scientific Evnts: *Scientific Apparatus and Laboratory Methods:Scientillc Events: Another Circuit for Temperature Controls: DR.The One Hundredth Anniversary of the Establish- BRADFORD NOYES. Another Method for Recordingmeant of the Alexander Dallas Bache Magnetic Ob- Localities from Topographical Maps: LESLIE HU-servatory; Pan-American Union against Cancer; BRICHT and RALPH 0. ERICKSON. A ConvenientThe Nineteenth Annual Plant Science Seminar; Method of Labeling Bottles: DR. CHARLES GuR-The Union College Science Symposium; The Hun- CHOT and JACK K. FINNEGAN..... 286dredth Anniversary of the New York University Science News ......... 6College of Medicine; Physicists and NationalDefense .......... 272 -

SCIENCE: A Weekly Journal devoted to the Advance-Scientific Notes and News .... ............... 275 ment of Science, edited by J. MCKEEN CATTELL and pub-

lished every Friday byDiscussion: THE SCIENCE PRESSThe Museums of New York: MUSAEUS. TheECR Is Progressing: PROFESSOR C. A. JACOB- Lancaster, Pa. Garrison, N. Y.SON. Pigeon Malaria in California: PRoFEssoR New York City: Grand Central TerminalCARL G. KADNER. Specificity of Renin: DR. DAVIDTURNOFF and DR. L. G. ROWNTREE .278 Annual Subscrption, $6.00 Sigle Copies, 15 Cts.

SCIENCE is the official organ of the American Associa-Scientific Books: tion for the Advancement of Science. Information regard-Mathematic.7: PROFESSOR RUDOLPH E. LANGER. Ing membership In the Association may be secured from

the office of the permanent secretary In the SmithsonianBadiologic Physics: DR. G. FAILLA .. .... 281 Institution Building, Washington, D. C.

EVOLUTION OF THE GERM-PLASM1By Professor C. E. McCLUNG

EMERITUS PROFESSOR OF ZOOLOGY, UNIVERSITY OF PENNSYLVANIA; VISITING PROFESSOR

OF ZOOLOGY, UNIVERSITY OF ILLINOIS

A DEFINITION of terms seems to be the first requisitein a discussion of this subject. By "germ-plasm" we

mean a distinctive substance, endowed with all the

properties of life, but especially with that of repro-duction, which here is, in some measure, unique.Equivalence is an inherent characteristic of organicreproduction, and it holds in respect to the germ-plasm itself; but, whereas commonly the influence of

a part is continuously the same, that of the germ-plasm is cyclically different. It involves elements

which mark the race and so it may be denominated

"racial material." It is customary to distinguish be-

tween "germ-plasm" and "soma-plasm," both beingnuclear, one concerned with racial processes, the other

'Presented at the University of Pennsylvania Bicen-

tennial Conference, September, 1940.

with those of the individual. This distinction is, how-ever, purely arbitrary and may lead to misunderstand-ings. Such a distinction was suggested by the pre-sumed functional differences between the macro- andmicronuclei of certain Protozoa. But if the germ-plasm is defined specifically as "that substance, or

organization, which distinguishes a chromosome com-

plex" then it is essentially the same in both germ andsomatic cells. Mere observations tell us that the chro-mosome complement of germ and somatic cells is one,both being derived by direct descent from that of the

original zygote. Finally, and in a more abstractsense, the germ-plasm may be defined as "the tem-

poral record of racial experience." However con-

ceived, it has the properties of continuity, specificityand control of organic processes.