The threat of takeovers is beginning to influence German business strategy. Slumping profits and worries about a possible raid helped push Schering ag, a $4 billion-plus German drug and chemical concern, to spin off two of its five divisions to Witco Corp. of New York for about $400 million. A third may also be sold, bringing both the work force and sales down by a total of 20%. The company wants to focus on drugs and agricultural chemicals. Schering has antitakeover measures in place, but Chairman Giuseppe Vita is said to privately admit that he cant count on them anymore. Other German companies could follow suit in slimming down.