(particularly those based on diffusion) as primary causative 

 agents in morphogenesis. He postulates that the synthesis of 

 the diffusible factors which play a role in his theory ("in- 

 ductive stimulus" and "stabilizer" substances) again depends 

 indirectly on the presence of cell-unique proteins, which them- 

 selves are under strict genetic control in the way suggested 

 earlier . 



The author is of course aware of the fact that Sperry's 

 "chemical neurospecif icity" hypothesis is currently under at- 

 tack, notably by Gaze. He claims, however, that on the basis of 

 his theory a reconciliation of the views of Sperry (and partly 

 of Weiss) with those of Gaze is possible. He rejects Weiss' 

 modulation hypothesis and proposes instead a "principle of al- 

 ternative matching" between chemically uniquely specified 

 cells, which distinguishes between optimal and suboptimal 

 matching of cell surfaces. 



The theory bears a pronounced unitarian stamp and encompasses 

 several biological problems falling outside embryology in the 

 strict sense, such as antibody formation, connectivity in the 

 nervous system, and cell contacts generally. The embryological 

 areas of application are reaggregation and cell sorting, morpho- 

 genetic movements, establishment of embryonic axes, and devel- 

 opmental stability and regulation. With respect to cell con- 

 tacts the author extensively discusses the views of Curtis, 

 with whom he disagrees to the point of becoming polemical. The 

 latter two subjects are discussed on the basis of a few select- 

 ed examples, mainly taken from the work of Driesch, Roux, and 

 HSrstadius. The important problems of pattern formation and 

 pattern regulation are treated only in the most general manner, 

 without suggesting detailed mechanisms. This is definitely a 

 weak point in the whole theory. 



The theory certainly is novel and ingenious, and involves the 

 reversal of several traditionally accepted views. On these ac- 

 counts alone, at least its basic assumptions deserve the atten- 

 tion of developmental biologists, if only to stimulate further 

 discussion of these important problems. Only the future can 

 show to what extent the theory is valid as it stands, but it 

 may be a long time before it can be critically tested by ex- 

 periment . 



7. 



A.I.ZOTIN. 1972. THERMODYNAMIC ASPECTS OF DEVELOPMENTAL BIOLOGY 

 Karger, Basel, etc. Monographs in Developmental Biology. Vol.5. 

 VIII, 159 pp., 30 figs., 23 tabs. Sfr. 66.00, $ 18. 50, £ 7.30 



Contents: I. Thermodynamics of irreversible processes: basic 

 information; II. The Prigogine-Wiame thermodynamic theory of 

 growth and development; III. Constitutive approach of the 

 living systems to the final stationary state; IV. Constitutive 

 deviation of living systems from the steady state; V. A pos- 

 sible molecular mechanism of the constitutive processes; VI. 

 Thermodynamic theory of growth 



This interesting monograph is devoted to an elaboration of 

 the ideas of Prigogine and Wiame, who in 19^6 suggested that the 

 main equations and concepts of the thermodynamics of irrevers- 

 ible processes might be applicable to animal growth and develop- 

 ment. The author is head of the Laboratory of Biophysics, Insti- 

 tute of Developmental Biology, Academy of Sciences of the USSR. 

 He and his colleagues have published a considerable amount of 

 experimental and theoretical work on the metabolism and ener- 



187 



