232 K. E. VON BAER. PHILOSOPHICAL FRAGMENTS. 



(p. 257.) FOURTH COROLLARY. 



******* 



But from what has been said, it seems to follow that every 

 principal type of animal organization follows a special scheme 

 of development ; indeed nothing else could have been expected, 

 since the mode in which the parts are united together can only 

 be the result of the mode of development. In reality, therefore, 

 I might have used, instead of Type and Scheme, a common term 

 expressing both. I have only kept them separate in order so 

 to make it obvious, that every organic form, as regards its type, 

 becomes by the mode of its formation that which it eventually is. 

 The scheme of development is nothing but the becoming type, 

 and the type is the result of the scheme of formation. For that 

 reason the type can only be wholly understood by learning the 

 mode of its development. This introduces differences into the 

 germs, which at first are alike in all essential points. Different 

 conditions or formative powers must act upon the germ in order 

 to produce this multiplicity, on which head we shall by and by 

 raise one or two queries. 



Here, however, we must add the remark, that the original 

 agreement of all animal germs does not completely disappear 

 even in the perfect forms, and that we have to seek the most 

 profound distinctions among animal forms, which are attainable 

 by us in the mode of development. 



With respect to the original agreement, I would call to mind, 

 that, according to the Corollary of the Second Scholium, every 

 animal is at first a part of its mother, that it becomes indepen- 

 dent either by the immediate development of the parent herself, 

 or after the action of a male principle, and that then the first 

 act of independence consists in passing into a vesicular form ; 

 either the whole becoming the body of the new animal, or the 

 future body (the germ) separating itself from the merely nutri- 

 tive substance which surrounds it. Here animals and plants 

 diverge, since the latter do not invest the nutritive matter. 

 The vesicular form, therefore, is the most general character of 

 the animal ; the contrast of external and internal surface is the 

 most general, and therefore the most essential contrast in the 

 animal. (See above, Schol. V. 4 d.) 



