Section II 

 METHODS AND TECHNIQUES 



JANE M. OPPENHEIMER 



INTRODUCTION: SOME GENERAL 

 CONSIDERATIONS 



Great advances, in scientific history, have 

 almost always depended more on intellectual 

 than on technological innovations. No new 

 technique has alone either answered any 

 problem of primary importance or has itself 

 set one. In biological history, specifically, so 

 far as technique is concerned, the work of 

 Harvey and of Darwin and of Mendel could 

 have been performed far earlier than it was: 

 their advances were on the intellectual side, 

 rather than technical in any sense. Harvey's 

 greatest contribution was perhaps the appli- 

 cation of the principle of measurement to 

 biological material, and his ability to per- 

 form his experiment was an inevitable out- 

 come of his quantitative considerations. There 

 was a certain greater ease for him, who was 

 bred in the halls of Padua a generation after 

 Galileo, than for his predecessors to think 

 quantitatively. But there is no a priori rea- 

 son why such thinking might not have 

 emanated from some Greek mind near Archi- 

 medes who in considering specific gravity in 

 physical terms was thinking as quantitatively 

 as Harvey who had only to collect and count 

 a few cups of blood. Darwin was led to the 

 formulation of his doctrine by the considera- 

 tion of Malthus' economic principles and 

 Ly ell's geological ones: but might not a clue 

 to the genetic relationship of man and the 

 ape have come from a comparison of their 

 faces? Indeed had it not already done so in 

 Buffon's concept of the ape as a "degraded" 

 man? And what did Mendel do but sepa- 

 rate his generations, keep careful records, 

 count accurately and think clearly? The ma- 

 terial of these men was the organism pure 

 and simple; the instruments with which they 

 attacked it were primarily their ideas. To 

 quote Woodger, who emphasizes the same 

 point: 



Neither Dalton nor Mendel were afraid to put 

 forward their hypotheses because of the absence of 



physical apparatus like that provided by X-ray pho- 

 tography. Their hypotheses were devised to explain 

 the generalizations of their day — chemical general- 

 izations about combining proportions in Dalton's 

 case, and generalizations about ratios of kinds of off- 

 spring of known parentage in Mendel's case. The 

 apparatus which subsequently provided confirma- 

 tion of these hypotheses might never have been in- 

 vented (at least in the case of Dalton) if the hy- 

 potheses themselves had not first been invented 

 ('48, p. 360). 



In embryology, too, as we have seen, the 

 concept developed before the technique to 

 verify or refute it. It was changes in think- 

 ing, not the mechanical tool, that permitted 

 Wolff and von Baer to see more than Mal- 

 pighi, in seeing less. Thinking in terms of 

 concrete units such as Dalton's atoms, Men- 

 del's unit characters in heredity and Pasteur's 

 germs preceded the discovery and observation 

 of discrete particles in the form of chromo- 

 somes and cytoplasmic inclusions by the use 

 of improved achromatic lenses in the mas- 

 terly cytological studies at the turn into the 

 present century that were to become so im- 

 portant for embryology. Boveri ('07) estab- 

 lished the fact of qualitative difference of 

 the chromosomes by an intellectual tour de 

 force in his analysis of dispermic echinoderm 

 eggs before the technical methods of genetics 

 were available. Spemann reached his primary 

 premises out of thoughtful consideration of 

 methodologically simple constriction experi- 

 ments; he was later only to test and confirm, 

 by the application of the technically more 

 involved transplantation methods of Born 

 and Harrison, what he had already suspected. 



Indeed, one of the more curious phenom- 

 ena of embryological history is the great 

 lag in the application of more general bio- 

 logical techniques to the particular problems 

 of embryology. Vesalius' Fabrica was pub- 

 lished over 75 years before the treatise of 

 Fabricius on the developing chick. Strong 

 magnifying lenses were used fruitfully for a 

 half century on other biological material be- 

 fore Malpighi used the compound micro- 



25 



