[Letters to Editor]

Abstract

WHEN writing the book referred to by Dr. Kennedy, we were frequently faced with the alternatives of inventing new technical terms (which are often resented by the people who have to learn and use them) and of using common words in newly defined ways (which causes trouble because it is difficult to exclude from one's mind some of the common implications of the words). If Dr. Kennedy, who has studied insect activity and aggregation in the field as much as anyone, has to make an excessive mental effort with 'low' and 'high' kinesis, then the generality of zoologists must find them very troublesome indeed. The advantage of the broad use of 'photo-negative' is that it can be applied to a particular reaction before one knows which type of behaviour is responsible for aggregation in the dark. 'Positive' photo-kinesis can lead to photo-negative behaviour. If this awkwardness of signs is generally thought to be preferable to the ambiguity to which Dr. Kennedy directs attention, then let us use his modification of the system of terms.