THEODOR SCHWANN 271 



to each other, the view would leave entirely unexplained how the ele- 

 mentary parts of organisms, that is, the crystals in question, become 

 united to form a whole. It is therefore necessary to show that crys- 

 tals do unite with each other according to certain laws, in order to per- 

 ceive, at least, the possibility of their uniting also to form an organism, 

 without the need of any further combining power. But there are 

 many crystals in which a union of this kind, according to certain laws, 

 is Indisputable ; indeed they often form a whole, so like an organism in 

 its entire form, that groups of crystals are known in common life by 

 the names of flowers, trees, etc. I need only refer to the ice-flowers 

 on the windows, or to the lead-tree, etc. In such instances a num- 

 ber of crystals arrange themselves In groups around others, which 

 form an axis. If we consider the contact of each crystal with the 

 surrounding fluid to be an indispensable condition to the growth of 

 crystals which are not capable of Imbibition, but that those which are 

 capable of imbibition, in which the solution can penetrate whole layers 

 of crystals, do not require this condition, we perceive that the simi- 

 larity between organisms and these aggregations of crystals is as great 

 as could be expected with such difference of substance. As most cells 

 require for the production of their metabolic phenomena, not only 

 their peculiar nutrient fluid, but also the access of oxygen and the 

 power of exhaling carbonic acid, or vice versa; so, on the other hand, 

 organisms in which there is no circulation of respiratory fluid, or in 

 which at least it is not sufficient, must be developed in such a way as 

 to present as extensive a surface as possible to the atmospheric air. 

 This Is the condition of plants, which require for their growth that the 

 individual cells should come into contact with the surrounding medium 

 in a similar manner, if not in the same degree as occurs in a crystal 

 tree, and In them indeed the cells unite Into a whole organism in a 

 form much resembling a crystal tree. But in animals the circulation 

 renders the contact of the individual cells with the surrounding me- 

 dium superfluous, and they may have more compact forms, even 

 though the laws by which the cells arrange themselves are essentially 

 the same. 



The view then that organisms are nothing but the form under which 

 substances capable of imbibition crystallize, appears to be compatible 

 with the most Important phenomena of organic life, and may be so far 

 admitted, that it is a possible hypothesis ; or attempt towards an ex- 



