Two possibilities of using computers which seem most likely to influence taxonomy are: (1) A replacement of our present taxonomic system with a completely logical (Aristotelian) system in which each taxon to which any organism belongs would be designated by a digit in an alphanumeric code number of not more than eleven digits for each species. The code number would therefore contain the complete classification of the organism. (2) The determination of relationships between taxa by means of computers which also can compile a complete taxonomic system based on similarity coefficients. This system called numerical taxonomy. In order to accept the first of these possibilities it will be necessary to discard all of the present rules of nomenclature. In order to accept the second of the possibilities it will be necessary to discard not only the rules of nomenclature but also all the other aspects of the present system and let the machines take over all phases of taxonomy except the recording of data. During the last decade computers have been applied to taxonomic problems in various ways (review, Jahn, 1962), and it seems highly probable that these applications will become both more extensive and more intensive. My purpose today to point out the direction of some of these applications and also some of their possible effects on the science of taxonomy as it now exists. However, in case there might be persons present who are not familiar with the scope of computer activities, I wish to state briefly what meant by the term computer. A computer a machine that performs logical operations. It a tool of the mind, comparable in many respects to the way a power saw a tool of the hand. Computer techniques comprise the central core of the field of intellectronics. The goal of intellectronics is to achieve a synthetic intelligence, part human and part mechanical, which combines the strongest features of both, to produce a new order of intellectual power exceeding that of either man or machines operating separately (Physics Today, March 1961, back cover). Therefore, intellectronics may be considered comparable to that field of engineering concerned with the design and operation of power machinery. In moder civilization not using a computer for a logical operation when it would be of help comparable to sawing wood by hand, or, on a larger scale, comparable Received for publication 13 August 1962. *Aided by ONR Contract NR-304-502 and USPHS-NIH grant No. 6462. to making an automobile by hand. It can be done but why do it that way?-except, of course, as a hobby. The simplest jobs for computers involve only arithmetic. The more complicated applications of arithmetic involve bookkeeping, especially payrolls, for which computers use information on rates of pay, number of hours worked, overtime rates and hours, social security tax rates, rules for tax deductions and for miscellaneous deductions, vacation time permitted and taken, etc. On the basis of these rules paychecks are issued or credited at a local bank. The complete calculations are made in small fractions of a second. In a similar way computers can perform statistical analyses and determine coefficients of similarity with extreme speed and accuracy, and this one of the computer techniques that has been used to great advantage in taxonomy in a manner to be described below (Sneath and Sokal, 1962; Ehrlich, 1962b; Daly, 1962). A more complicated common job for computers involves solving differential equations. The extreme rapidity by which this can be done by computer completely essential to the flight of both guided and ballistic missiles. Furthermore, it possible for computers to obtain arithmetical solutions to differential equations that are insolvable by the usual methods of calculus. A different application involves translation from one language to another. The languages used can be either human languages or the languages used by other types of machines