DEVELOPMENT. 167 



which do not obviously come under any of these heads. He 

 may point to plants that are for a time multicentral but after- 

 wards develop axially. And from lower types of animals he 

 may choose many in which the continuous and discontinuous 

 modes are both displayed. But, as already hinted, an ar- 

 rangement free from such anomalies must be impossible, if 

 the various kinds of organization have arisen by Evolution. 

 The one above sketched out is to be regarded as a rough 

 grouping of the facts, which helps us to a conception of them 

 in their totality ; and, so regarded, it will be of service when 

 we come to treat of Individuality and Reproduction. 



§ 51. From these most general external aspects of organic 

 development, let us now turn to its internal and more special 

 aspects. When treating of Evolution as a universal process 

 of things, a rude outline of the course of structural changes in 

 organisms was given {First Principles, §§ 110, 119, 132). 

 Here it will be proper to describe these changes more fully. 



The bud of any common flowering plant in its earliest 

 stage, consists of a small hemispherical or sub-conical pro- 

 jection. While it increases most rapidly at the apex, this 

 presently develops on one side of its base, a smaller projec- 

 tion of like general shape with itself. Here is the rudiment 

 of a leaf, which presently spreads more or less round the base 

 of the central hemisphere or main axis. At the same time 

 that the central hemisphere rises higher, this lateral promi- 

 nence, also increasing, gives rise to subordinate prominences 

 or lobes. These are the rudiments of stipules, where the 

 leaves are stipulated. Meanwhile, towards the other side of 

 the main axis and somewhat higher up, another lateral pro- 

 minence arising marks the origin of a second leaf. By the 

 time that the first leaf has produced another pair of lobes, 

 and the second leaf has produced its primary pair, the central 

 hemisphere, still increasing at its apex, exhibits the rudiment 

 of a third leaf. Similarly throughout. While the germ of 

 each succeeding leaf thus ariseS, the germs of the previous 

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