THE ENERG Y OF E VOL UTION. 489 



tissues like those of the parent and without interfer- 

 ence. Here we have the molecular energy of the par- 

 ent converted into the molar movements observed to 

 be concomitants of segmentation ; to be represented 

 in the completed tissue by the mutual tensions by vir- 

 tue of which each structural element maintains its in- 

 tegrity. It is evidently a process of metamorphosis of 

 energy in which there is less waste than in any other 

 known to us. Embryonic growth is accompanied by 

 a very slight dissipation of heat, since a slight rise 

 of temperature is noticeable in the eggs of cold-blooded 

 animals and in flowers, when reproduction is active. 

 The products of breaking down are equally rare in 

 embryonic growth, and both this and the dissipation 

 of heat are perhaps largely due to the changes wrought 

 in non-cleavable nutritive substances with which the 

 yolks are sometimes charged. It is probably to ac- 

 complish this process that the oxygen necessary for the 

 embryonic growth is used. How much loss is due to 

 cell-division itself is not known, but it must be very 

 little if any. We have probably here a nearly perfect 

 conversion of energy. Theoretically we have ana- 

 genesis wherever the up-building exceeds the down- 

 breaking. 



The attempt to realize in the imagination the 

 modus operandi of bathmic energy in embryo-building 

 takes the following form. It is to be supposed that 

 movement which has been most frequently repeated, 

 and for the longest period, is prepotent, and takes 

 precedence of all others. This is clearly simple cell- 

 division, which follows the nutrition supplied by the 

 spermatozoon, and which represents the first act of 

 animal life. Hence, segmentation of the oosperm is 

 the first movement of bathmism. Each subsequent 



