ABSTRACT
To speak of ‘the problem of morphogenesis’ implies that there is some single crucial secret to be discovered, which, when known, will indicate the lines along which all morphogenetic phenomena are to be interpreted. The information-containing molecules, as we meet them in the flesh, have a very well-developed 3 D form. Forms or patterns must be discussed in connection with the notion of buffered developmental pathways. The studies on pattern formation in Drosophila have produced examples of nearly all these types of elementary alterations. The pattern is quite invariable in normal ‘wild-type’ or unselected stocks, even in extreme culture conditions, although occasional variants do occur. The pattern can therefore be said to be highly chreodic, or very well canalized. The scutellar bristle pattern has been extensively studied, but almost nothing is known of the developmental processes leading to the initiation of bristles in Drosophila.
