Formed Constituents of Organisms 169 



the process is happily preserved to us still, in forms left alive 

 at the present day. But, since some of the members in the 

 direct line of ascent have been blotted out, we are compelled 

 to seek for their restoration by piecing together information 

 yielded by remotely connected species, genera, or even tribes. 



Now in the whole of this evolving process we witness almost 

 entirely two changes proceeding. First, we observe an increas- 

 ingly discrete and expansive placing of substances already 

 in existence, including the exact number and position of each 

 new cell-partition; second, this discrete placing causes a corre- 

 sponding localization of functional activities. In other words 

 we would clearly assert that, between a Chlamydomonas indi- 

 vidual and one of the highest algae, the only possible differences 

 might be a more detailed distribution of cell constituents, 

 through changes in lines of energy-flow, therefore of growth- 

 activity, and so of material distribution; while attendant on 

 this and even inaugurating it is a like distribution of responses 

 to environal stimuli, or to these when they have reflexly become 

 intrinsic stimuli. The fundamental conception, back of the 

 changes, consists in changing lines of flow, and changing inten- 

 sities in the lines of flow, of energy distributed throughout 

 the organism. The molecules that register tliis openly for 

 us need not be altered in a single atomic detail. The quantity 

 and kind of molecules placed constitute the register of the 

 activity and distribution of energy flow. 



But if — as in the transition from aquatic to land plants — 

 a definite new chemical compound appears, e. g., lignin, cutin, 

 or possibly a glucoside or alkaloid, such represent "new char- 

 acters" in the strictest sense of the word. 



So here an important consideration presents itself. If we 

 are to reach an accurate and measurable estimate of evolu- 

 tionary change and modification, account must be taken min- 

 utely of every minute change in cell form, size, substance, and 

 environal action along with resultant response. The writer 

 has already emphasized this as a prime necessity (6^, 2: 20'2), 

 and was deeply impressed by it in his microscopic study of 

 plant hybrids (63: 271). But in ordinary taxonomic descrip- 



6* 



