214 ` The American Naturalist. [March, 
is not known, but it must be very little if any. We have here 
a nearly perfect conversion of energy. Theoretically we have 
anagenesis wherever the up-building exceeds the down-break- 
ing. 
The attempt to realize in the imagination the modus oper- 
andi of bathmic energy in embryo building takes the follow. ~ 
ing form. It is to be supposed that movement which has been 
most frequently repeated, and for the longest period, is prepo- 
tent, and takes precedence of all others. This is clearly sim- 
ple cell division, which follows the nutrition supplied by the 
spermatozo6n, and which represents the first act of animal life. 
Hence, segmentation of the odsperm is the first movement of 
bathmism. Each subsequent movement appears in the order 
of potency, which is, other things being equal, a time order, 
or the order of record. The cause of the localization of tissues 
and structures is much more difficult to understand than the 
cause of the order of their appearance. The more energetic 
part of the process naturally requires the greater space for its 
products. The ectoderm, which becomes the seat of the ner- 
vous axis and its muscular adjuncts, occupies the superficial 
portions of the yolk. Hence, we may regard this expression 
of the structural record of these functions as more energetic 
than that of the record structure of the nutritive functions, 
which displays itself below the ectoderm. In meroblasti¢ 
and amphiblastic embryos, the segmentation which develops 
the nutritive tissues is evidently more sluggish, for the cells are 
larger and fewer in number than those of the ectoderm. 
Can this difference in the segmentations which produce the 
ectoderm and the endoderm be due to a certain polarity; the 
male or energetic tendency predominating in the former, an 
the female in the latter? 
External stimuli modify the course of statogeny above de- 
scribed, and by producing new structural records cause à es 
form of energy, due to composition of the new with the mp 
and the process of growth then becomes bathmogeny: ~., 
external stimuli are molecular or molar, determining physic: 
bathmism or kinetobathmism. 
