DEVELOPMENT 221 



behaviour : it destroys, or impairs neurone-configurations (nerve- 

 tracks and synapses) and so also motor habits. But it seems to 

 be certain that the memory-image need not be obhterated. 



76^. Development — Hypotheses and Practical Investiga- 

 tions. Preoccupation with the psycho-biological conception 

 appears to (though it need not) inhibit the practical investigation, 

 morphological and physiological, of embryogenies. It is not yet 

 a working hypothesis and even if it were its methods would not 

 be physical-chemical ones. Beyond doubt there is immense 

 interest in the details of embryogenies, as studied by the micro- 

 scope ; in life-histories on the extended scale ; in the physio- 

 logical and bio-chemical events of a development and in the study 

 of the conditions of the environment. What the minute morph- 

 ology of the cell-nuclei of germ-cells and embryonic complexes 

 will yet reveal is not certain ; it is possible that the cytology of 

 the future will be a chromosomal physiology instead of a pure 

 morphology, as at present. It is probable that we shall see in these 

 minute systems only the apparatus of assimilation and not that 

 of embryogenic tectonics. 



All the more (should it prove true that the embryogeny of an 

 organism is a habit sustained by unconscious memory) may 

 we expect the development of an animal to throw light on the 

 past of the race — on the phylogeny of the groups represented 

 by the animal. That, of itself, would be a result of very great 

 interest since, as we shall see, it may be that the palaeontological 

 records of that phylogeny are irremediably destroyed. 



