only in connection with the previous and the future condi- 

 tions, in connection with the present. The essence of life 

 itself is considered the course of the vital process, i.e. a 

 series of conditions following one after the other. Of the 

 source of this change, Baer spoke with a certainty excluding 

 all doubt. 



We cannot leave without discussing the idle 

 argument about the vital power, that matter 

 goes only by necessity, causing all the momen- 

 tary conditions of organization that follow 

 one after the other .... In order to make 

 this more obvious , we say that in organic 

 life, each separate condition is only a 

 momentary expression of formation, or that 

 the settled condition is only a making visible, 

 and that formation is essence and permanence . 18 



The latter condition is the consequence of the previous, 

 not only by time, but also in relation to their internal 

 conditions. To illustrate, Baer mentioned the example of 

 the butterfly, whose imaginal condition is anticipated and 

 conditioned by the pupa stage, the condition of the pupa by 

 the caterpillar stage, the condition of the caterpillar by 

 the stage of the ovum appearing in the mother. The source 

 of material for all these transformations is, according to 

 Baer, the plant food used by the caterpillar. The materials 

 taken up as food are processed in the caterpillar into reserve 

 products which are used in the following conditions. The 

 vital process of the developed insect "needs food — we call 

 this demand hunger — thus, it demands enough food to suffice 

 it not only for the intensive growth of the caterpillar, but 

 also for the creation of reserves for future stages. "19 



Baer especially underlined the connection of these 

 conditions, processes and preparatory changes with the final 

 condition; in their resulting "from a spherical or ellipsoidal 



18. Ibid . , pp. 52-53. The same idea was stated by Baer in the 

 speech "Welche Auf f assung der lebenden Natur ist richtige ' 

 delivered at the opening of the Russian Entomological 

 Society in 1860 (REDEN, I, 1864, p. 268). 



19. Ibid ., pp. 53-54. 



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