128 



HABIT AND INTELLIGENCE, 



[chap. 



Sarcode. 



"White 

 blood-cor- 

 puscles. 



"Why the 

 higher ■ 

 organisms 

 do uot live 

 when, cut 

 in. pieces. 



Propaga- 

 tion by 

 sponta- 

 neous 

 division, 



Echinoderms mentioned above, and many others, have 

 shown that such is not the case. 



In speaking of the gromia, we have seen that germinal 

 matter will produce formed material, but formed material 

 will not produce germinal matter. In the case of the higher 

 organisms, it is of course impossible to give the same 

 experimental proof; but all evidence and aU analogy leads 

 to the conclusion that the same relations hold throughout 

 the whole organic creation. Germinal matter, similar in 

 appearance and general properties to the sarcode, or gela- 

 tinous living substance of such organisms as amceba, gromia, 

 and hydra, is found in the tissues of all living organisms, 

 and is most abundant in those which are gi'owing most 

 rapidly. It is also found in the blood : the " white blood- 

 corpuscles " consist of this germinal matter, and are with- 

 out structure, but show their vitality by spontaneous 

 movements like those of an amceba. 



But it may be objected to this theory, that if the forma- 

 tive powers of an organism reside in the as yet unorganized 

 germinal matter dispersed through it, a cut-off part of one 

 of the higher organisms ought to manifest independent 

 vitality, like a cut-off part of a hydra, which, in virtue of 

 its germinal power, will transform itself into a complete 

 hydra. 



I reply, that the difference in this respect between the 

 lowly hydra and the highest organisms, such as an elephant 

 or a man, consists in this : that any fragment of a hydra's 

 body can live wherever it has water and food ; but the 

 germinal matter of the higher organisms has no such 

 power — it can only live within the body of an individual 

 of the species to which it belongs, and when this is greatly 

 injured its germinal matter dies with it. 



The same difference explains the difference between the 

 mode of propagation among the lowest organisms and the 

 highest ones. It is probable, though not yet certain, that 

 true sexual generation is universal among all organic 

 species. But the lowest organisms, such as the Ehizopods 

 among animals and the Dijiitomaceae among plants, often 

 propagate by spontaneous division : the organism separates 



a/' 



