neither och either?

either. 1. The pronunciation ī-, though not more correct, has almost wholly displaced ē in England, though not in U.S.
2. The sense each of the two, as in the room has a fireplace at e. end, though more naturally expressed by each, cannot be considered unidiomatic.
3. The sense any one of a number (above two), as in e. of the angles of a triangle, is loose, any or any one should be preferred.
4. The use of a plural verb after e., as in if e. of these methods are successful, is a very common grammatical blunder.
5. Either ... or. In this alternative formula e. is frequently misplaced. This should be avoided in careful writing, but is often permissible colloquially. There are two correct substitutes for You are e. joking or have forgotten. Some writers refuse one of these, You e. are joking or have forgotten, on the ground that it looks pedantic; but there is no such objection to the other, E. you are joking or you have forgotten. In conversation, however, the incorrect form is defensible because a speaker who originally meant to say (are) forgetting (corresponding to are joking) cannot, when he discovers that he prefers have forgotten, go back without being detected (as a writer can) and put things in order. Some examples follow of the slovenliness that should not be allowed to survive proof-correction.
...unless it sees its way to do something effective e. towards keeping the peace or limiting the area of conflict. / Their hair is usually worn e. plaited in knots or is festooned with cocks' feathers. / It is not too much to say that trade unions e. should not exist, or that all workers should join compulsorily. / The choice before the nations will be e. that of finding a totally different and far better method of regulating their affairs, or of passing rapidly from bad to worse.
Either ... or is sometimes not disjunctive, but equivalent to both ... and or alike ... and: The continuance of atrocities, the sinking of the Leinster, the destruction of French and Belgian towns and villages, are a fatal obstacle either to the granting of an armistice or to the discussion of terms. In such cases, alike (or both) ... and should be preferred, or else proper care should be taken with either, ’an obstacle to either granting an armistice or discussing terms’ would do it.

neither. 1. Pronunciation. 2. Meaning. 3. Number of the pronoun and adjective. 4. Number and person of verb after neither ... nor. 5. Position of neither ... nor. 6. Neither ... or. 7. Neither as conjunction. 8. Neither pleonastic.
1. The pronunciation recommended is ī, not ē; see EITHER.
2. The proper sense of the pronoun (or adjective) is ’not the one nor the other of the two’. Like either, it sometimes refers loosely to numbers greater than two (Heat, light, electricity, magnetism, are all correlatives; neither can be said to be the essential cause of the others); but none or no should be preferred; cf. EITHER 3. This restriction to two does not hold for the adverb (Neither fish nor flesh nor fowl).
3. The number of the adjective and pronoun is properly singular, and disregard of this fact is a recognized grammatical mistake, though, with the pronoun at least, very common: The conception is faulty for two reasons, neither of which are noticed by Plato. / What at present I believe neither of us know. Grammar requires is noticed, and knows. he same mistake with the adjective is so obviously wrong as to be almost impossible; not quite, however: Both Sir Henry Verney and Mr. Gladstone were very brief, neither speeches exceeding fifteen minutes. An almost equally incredible freak with the pronoun is: Lord Hothfield and Lord Reay were born the one in Paris and the other at the Hague, neither being British subjects at the time of his birth (as indeed neither could be unless he were twins).
4. Number and person after neither ... nor. If both subjects are singular and in the third person, the only need is to remember that the verb must be singular and not plural. This is often forgotten; the OED quotes, from Johnson, Neither search nor labour are necessary, and, from Ruskin, Neither painting nor fighting feed men, where is and feeds are undoubtedly required; and we may still read in journals of the highest standing, or hear from the B.B.C., such sentences as Official quarters in London are confident that neither President Eisenhower nor Mr. Dulles want an armed clash with China. / Comment in Paris is guarded as neither General de Gaulle nor the Foreign Minister are immediately available. / Neither Mr. Gaitskell nor Mr. Grimond have tried to minimize the Russian provocation in Cuba. The right course is not to indulge in
bad grammar ourselves and then plead that better men like Johnson and Ruskin have done it before us, but to follow what is now the accepted as well as the logical rule.
Complications occur when, owing to a difference in number or person between the subject of the neither member and that of the nor member, the same verb-form or pronoun or possessive adjective does not fit both: Neither you nor I (was?, were?) chosen; Neither you nor I (is?, am?, are?) the right person; Neither eyes nor nose (does its?, do their) work; Neither employer nor employees will say what (they want?, he wants?). The wise man, in writing, evades these problems by rejecting all the alternatives—any of which may set up friction between him and his reader—and putting the thing in some other shape; and in speaking, which does not allow time for paraphrase, he takes risks with equanimity and says what instinct dictates. But, as instinct is directed largely by habit, it is well to eschew habitually the clearly wrong forms (such as Neither chapter nor verse are given) and the clearly provocative ones (such as Neither husband nor wife is competent to act without his consort). About the following, which are actual newspaper extracts, neither grammarians nor laymen will be unanimous in approving or disapproving the preference of is to are or of has to have; but there will be a good majority for the opinion that both writers are grammatically more valorous than discreet: Neither apprenticeship systems nor technical education is likely to influence these occupations (why not have omitted systems?). / Neither Captain C. nor I has ever thought it necessary to ... (Neither to Captain C. nor to me has it ever seemed ...).
5. Position of neither ... nor. Which neither suits one purpose nor the other. Read which suits neither one purpose nor the other. Suits being common to both members should not be inserted in the middle of the neither member. Such displacement has been discussed and illustrated under EITHER 5, and need only be mentioned here as a mistake to be avoided.
6. Neither ... or. When a negative has preceded, a question often arises between nor and or as the right continuation, and the answer to the question sometimes requires care; see NOR and OR. But when the preceding negative is neither (adv.), the matter is simple, or being always wrong. Examples of the mistake: Diderot presented a bouquet which was neither well or ill received. / Like the Persian noble of old, I ask ’that I may neither command or obey’. Here again, to say that Morley and Emerson have sinned before us is a plea not worth entering.
7. Neither alone as conjunction. This use, in which neither means ’nor yet’ or ’ and moreover ... not’, and connects sentences instead of the ordinary and not or nor (I have not asked for help, neither do I desire it; Defendant had agreed not to interfere, neither did he) is much less common than it was, and is best reserved for contexts of formal tone. But it is still fully idiomatic where it links the speaker with some other person: Defendant did not interfere; neither did I.
8. Neither with the negative force pleonastic, as in I don't know that neither (instead of either), was formerly idiomatic though colloquial, but is now a vulgarism. Nor should a pleonastic one be attached to neither, as in neither one showed much courage.