PHYSIOPHILOSOPHICAL SYSTEMS.

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tendencies, the more heterogeneous are the elementaryparts which this life brings into action. The same is trueof the single parts of any apparatus. That organizationis higher in which the separate parts of an entire systemdiffer more among themselves, and each part has greaterindividuality, than that in which the whole is more uni-form. I call type the relations of organic elements andorgans, as far as their position is concerned. This relationof position is the expression of certain fundamental con-nexions in the tendency of the individual relations of life;as, for instance, of the receiving and discharging poles ofthe body. The type is altogether distinct from the de-gree of perfection; so that the same type may includemany degrees of perfection, and, vice versa, the same de-gree of perfection may be reached in several types. Thedegree of perfection, combined with the type, first deter-mines those great animal groups which have been calledclasses . 1 The confounding of the degree of perfectionwith the type of organization seems the cause of muchmistaken classification; and in the evident distinctionbetween these two relations we have sufficient proof thatthe different animal forms do not present one uniserialdevelopment from the Monad up to Man.”

The types he has recognized are:

I. The Peripheric Type. The essential contrasts inthis type are between the centre and the periphery . 2 The

1 From this statement it is plainthat Baer has a very definite idea ofthe plan of structure, and that hehas reached it by a very differentroad from that of Cuvier . It is clearalso that he understands the distinc-tion between a plan and its execu-tion. But his ideas respecting thedifferent features of structure are notquite so precise. He does not dis-tinguish, for instance, between the

complication of structure as deter-mining the relative rank of the orders,and the different ways in which, andthe different means by which, theplans are executed, as characteristicof the classes.

2 Without translating verbatimthe descriptions Baer gives of histypes, which are greatly abridgedhere, they are reproduced as nearlyas possible in his own words.