313 On the Qreen Matter luhich vegetates in IVaier. 



that the whole of the interior of thefe plants is cbmpofed of 

 the medullary part, in the middle of which are a few longi- 

 tudinal fibres. Thefe vegetables have no folidity but at the 

 furface, where the fibres are colle6led and united ; whereas 

 in the dicotyledons the furface is compofed of an epidermis, 

 which has little folidity, while the interior has a great deal. 



Though the green matter which vegetates in water has al- 

 ready been the objeft of much refearch to philofophers, Se- 

 nebitr has thought it worthy of being fubjefted to a new ex- 

 amination. He informs us, that it was known to Lahire, 

 Leuenhoeck, and Romberg. Adanfon gave it the name of 

 tremella conferva gel atlnof a ^omnium tenerrima, minima, aqua- 

 rum hmo innaj'cens. Prieftley, Ingenhouz, Senebier, Girod- 

 Chantram, made a variety of experiments and obfervations 

 on (his Angular fubftance. Felix Fontana believes it to be 

 a kind of polypier, that is the habitation of fmall infefts, 

 which produce it as other infefts produce coral. This is the 

 opinion alfo of Ingenhouz and Girod-Chantram; but Sene- 

 bier is of a different opinion. Having made refearches re- 

 fpe<Sling the manner in which this green matter is produced in 

 the water, he found, i. That it was never produced in water 

 kept in obfcurity : 2. That a great deal of time was requifite 

 to produce it in diftilled water, and that it was neceflary that 

 the water fliould be long expofed to the air': 3. That water 

 into which he had put earth, was more favourable than any 

 other to the produ6lion of this green matter : 4. That none 

 of it was formed in a veflel of water covered with a ftratum 

 of oil. 



To afcertain the manner in which it is formed, he put 

 glalTes, on which fome of the green matter had been, into 

 veflels of water, and perceived in the water, fome days after, 

 animalcula without green matteT. The green matter then 

 appeared, and he faw the animalcula penetrate into it, and 

 give it movement. At other times he faw the green matter 

 without animalcula. He obferved in this green matter a 

 very diftinft pellicle, fimilar to that of vegetables. This pel- 

 licle appeared to him to abforb the carbonic acid gas which 

 is in the water; to decompofe it ; to abforb the carbon; to 

 nourifh itfelf; and to fufFer the oxygen gas to be difengaged. 

 7 ' This 



