384 KANSAS ACADEMY OF SCIENCE. 



development, proceeded from the simple to the complex, from the un- 

 differentiated to the differentiated, and from the unpleasant to the 

 better. I would add as a probable hypothesis, in harmony with the 

 preceding, that in the development of the race conscious activities 

 preceded the habitual, the habitual preceded the subconscious, and 

 the subconscious the instinctive activities. By heredity the in- 

 dividual acquires in the beginning a large store of instinctive tenden- 

 cies; later the subconscious activities appear; and finally, when 

 independent existence is reached, the conscious and habitual activities 

 give the possessor freedom in his environment. 



No attempt will be made to prove this hypothesis by a course of 

 logical reasoning, for life is a variable factor, and the syllogism does 

 not apply in the life method, A few illustrative examples will be 

 taken here and there merely to show the general harmony of the 

 hypothesis with life methods. 



The mammalian egg, when fertilized by a sperm cell, begins at once 

 the work of segmentation, and the cells divide and subdivide till six- 

 teen or thirty-two cells are produced, arranged in the form of a sphere. 



This process of segmentation of the mammalian egg is entirely in- 

 stinctive, for it takes place blindly, after a fixed plan. It divides first 

 into two cells ; these two cells subdivide by a plane at right angles to 

 the first plane, forming four cells ; then these four cells subdivide by 

 planes at right angles to the other two planes and eight cells result. 

 This regular order of division planes is one of the distinguishing 

 differences between complex plants and animals. In all complex 

 plants the second, third and fourth planes are essentially parallel 

 with the first plane, and greatly elongated forms result. 



In the segmenting mammalian egg the first eight cells are arranged 

 roughly in the form of a cube ; then, as the segmentation continues, a 

 solid sphere is produced, the morula ; next a hollow sphere, the blastula ; 

 and then, by a process of unequal cell growth and invagination of 

 the blastula, a hollow cup is formed, the gastrula. 



We shall possibly find the nearest analogues of the mammalian egg 

 among the mouthless mastigopKora. Ninety-nine one-hundredths of 

 the j)rotozoa are provided with mouths, or have no cell-walls, or h&ve 

 very thin places in their cell- walls for the ingestion of solid food. A 

 mouth or its equivalent gives its possessor such an advantage in the 

 struggle for protozoan existence that its fortunate or, better, unfortu- 

 nate possessor lacks strong incentives for developing a structurally 

 more complex type of existence. 



The mouthless one-celled organism must live all his days as a 

 plant by absorbing carbon dioxide, water, and certain mineral salts, 

 and from these prepare starch, sugar, and proteids, or he may get part 

 of his nutriment this way and prepare digestive ferments, as do his 



