ALGAE — MEIER 425 



Asia, and America. They perforate calcareous substances of all 

 sorts from the Bryozoa and the tubes of worms to the strongest 

 rocks. They are responsible for the blue and green spots on the cal- 

 careous rocks of the coast, spots that may extend to 50 meters in 

 depth. They are especially common in the superficial layers of the 

 zone inundated by the waves of the sea, where they work in concert 

 with perforating animals such as sponges and mollusks. 



Not only animals, but calcareous algae such as Lithothainnion 

 undergo attacks from perforating algae. In the rivers of north- 

 west Russia the dissolving action of the perforating algae is exer- 

 cised not only on calcium carbonate, which they transform into 

 bicarbonates, but also on magnesium carbonate. This often accom- 

 panies calcium carbonate in mollusks and corals. The perforating 

 algae have a very ancient origin, dating back to the Silurian epoch, 

 as shown by evidences of their presence in fossil mollusks and 

 fossil bones of animals. 



The coral reefs of the Red Sea, Ceylon, Java, and the Bahama 

 Isles have sujffered from the destructive work of the perforating 

 algae. They invade not only the debris and the coralline sand but 

 also blocks detached from the banks and the coral reefs. The lower 

 part of the coral is often pierced by a whole canal of Ostreohium 

 reineJcei, which will bring about the rupture of the coral in this 

 place by the shock of the waves. It is certain that perforating 

 algae contribute to the formation of the atolls in taking part in the 

 destruction of the central part of the coral banks. It has also been 

 suggested that the factors controlling the depth at which reef -build- 

 ing corals can live may be determined by the suitability of the 

 conditions for the photosynthesis of the algae associated with the 

 coral formers. 



ALGAE GROWING IN A VACUUM 



Since algae grow in the soil, on the ground, on plants and ani- 

 mals, in the water, in the air — in short, in every conceivable natural 

 habitat — two scientists wondered if possibly they might grow in a 

 vacuum. Consequently they selected 48 species of the simplest forms 

 and, supplying them with a sufficient amount of nutrient solution, 

 placed them in a hennetically sealed bell jar from the inside of 

 which all traces of oxygen and carbon dioxide were removed. They 

 placed the bell jar in artificial light for 40 days. Of the 48 species, 

 10 were incapable of developing in these conditions, but their growth 

 subsequent to the removal of the bell jar proved that they had not 

 perished. Thirty-eight species developed in the vacuum. Those 

 algae that withstood the conditions especially well were aquatic 

 species. The vacuum prevented the production of chlorophyll, 

 starch, carotin, and xanthophyll. 



