     @radius = options.radius || 5
     @tick   = @universe.tick
     @babies = 0
+    @mark ||= null
     @belly ||= 'white'
+    @topicColor = null
   describe: ->
     description = super()
     description.health = @health()

  drawHunger: -> # show emptiness of belly
    h = @health()
    r = ( @radius - 1 ) * ( h - @hp ) / h
    @drawCircle @x, @y, r, @belly
    if @sickness?
      @drawCircle @x, @y, 3 * r / 4, @sickness.disease.color
  # maximum health points an organism can retain

                radius:      @radius
                bodyColor:   @bodyColor
                inheritMark: @inheritMark
                mark:        if @inheritMark then @mark else null
                belly:       if @inheritMark then @belly else null
                generation:  @generation + 1
              }
