68 PRIMITIVE FORMS OF LIFE 



the surface and from the light. There we see the first signs of 

 the method of nutrition adopted by animals. Oken's hypothesis 

 of a primeval slime (Urschleim) , out of which all animals and 

 plants have developed, is not therefore untenable. Organisms 

 in the form of a simple mass of slime are, indeed, so exceptional 

 that in all probability it was only after the pulverulent form 

 had been developed that the separation of the two kingdoms 

 took place, by means of a process analogous to that which we 

 have just described. 



The multiplication in situ, by fission, of these green granules, 

 each one enveloped in a membrane formed by the exudation 

 of carbo-hydrates not utilized in nutrition, must have sufficed 

 to form a thick layer of vegetable powder which the solar 

 light was finally unable to penetrate. The multiplication of 

 vegetable powder would be none the less continuous because 

 the nutrition had not been interrupted. Chlorophyll is only 

 produced under the influence of those invisible 1 or luminous 

 radiations which form the solar spectrum. These rays are 

 excluded as soon as the powdery mass has become sufficiently 

 thick, but this does not prevent excess soluble carbo-hydrates, 

 washed down by the dew, for instance, from passing into the 

 deeper layers. These deep-sunken granules, if sufficient in 

 number, continue to envelop themselves in cellulose and to feed 

 by absorbing dissolved substances, but they form no more 

 chlorophyll. Plants of this kind, which have no chlorophyll, 

 are known as fungi. Underneath these, in our hypothetical 

 layer of living granules, the carbo-hydrates are scarcer and 

 are completely absorbed during nutrition ; the granules 

 build no more cellulose exudate, and the living slime remains 

 free and mobile, as in the case of tan mould. Since 

 it translates the stimuli it receives into visible movements it 

 must consequently be sensitive. Mobility and sensitivity are 

 characteristics of the animal kingdom, which thus appear as 

 a degraded condition of primitive plant-life, to which is linked 

 such forms of mixed origin as the fungi. Mobility and 

 sensibility, however, have enabled the animals to come into 

 their own by other means, and to raise themselves to the 

 highest manifestations of life. 



1 It can be formed by the infra-red rays alone in various species of 

 microscopic algas (Chlorella, Dictyosphezrium, Hormococcus, Pleurococcus, 

 etc.), ferns, certain conifers, bulbous plants like onions or parasites like the 

 mistletoe. 



