70 PRIMITIVE FORMS OF LIFE 



life ; whether certain of its rays are not capable or, above all, 

 were not formerly capable of producing directly those com- 

 binations that enter into the constitution of all living matter. 

 Then we see how Daniel Berthelot and Gaudechon obtained 

 synthetic carbo-hydrates by the reciprocal action of carbon 

 dioxide and water, in the absence of any chlorophyll and 

 solely under the influence of ultra-violet rays emanating from 

 a tube of mercury vapour. The same rays enabled them to 

 obtain formamides through their action on a mixture of carbon 

 dioxide and ammonia gas. Formamide is the simplest of the 

 quaternary substances, of which the albuminoids are the most 

 complicated, and a combination of which constitutes the proto- 

 plasm which uses the carbo-hydrates as a food. Here we are on 

 the path that ought to lead us to the origin of life. At any rate, 

 it has been demonstrated that if certain ultra-violet rays kill 

 spores, others, on the contrary, are capable in themselves of 

 producing combinations which were for a long time believed 

 to be possible only if certain organic substances were already 

 present ; and it is these very rays that do in fact penetrate 

 our atmosphere. 1 



After giving his results, Berthelot adds : " The fundamental 

 reason for the efficacy of ultra-violet rays seems to be their 

 extremely high temperature. The higher the temperature of 

 the source rises, the richer it becomes in ultra-violet rays. 

 And when the reflection of a mercury-arc is projected upon that 

 of the solar disc we recognize by the physical phenomenon of 

 the displacement of the lines in the spectrum that the 

 temperature of this arc is greater than that of the sun." Now 

 it is certain that the portion occupied by ultra-violet in the 

 solar spectrum was at one time greater than it is to-day. 

 The sun, in fact, belongs to the group of yellow stars— A returns, 

 a i of Centaur, the Polar star, etc. It is now already colder than 

 Procyon and Canopus, which also belong to the yellow stars. 

 The sun was unquestionably, at some distant epoch, far hotter 

 than it is to-day ; we can even reconstruct the various stages 

 through which it has passed by studying the white and bluish 

 stars that are by far the hottest of all. Some of the white 

 stars, such as the majority of those in Orion and the Pleiades, 

 Regulus, the p of Centaur, Deneb, etc., are evidently the seat 

 of electrical discharges produced under very special conditions ; 



1 XVIII. 



