ORGANIZATION AND GROWTH 225 



about 200 per cent., is added to the sea-water, a remarkable 

 phenomenon occurs: large pieces of protoplasm escape 

 from the Tubulariae without losing their form. They are 

 surrounded by a transparent membrane which is formed per- 

 haps through their contact with the sea-water. I saw a 

 piece 12 cm. long escape from a Tubularian in this way. 



4. That an increased absorption of water by the tissues 

 favors regeneration when it does not exceed a slight amount ; 

 while a greater absorption is harmful, might seem contradic- 

 tory. But it is an entirely general and well-known fact that 

 when water enters cells in too large quantities it acts as a 

 poison. Hoppe-Seyler, for instance, attributes the death of 

 frozen plants which are thawed out too rapidly to the fact 

 that "in freezing, the water separates to a large extent from 

 the solids and collects in crystals. When thawed out rap- 

 idly, the particles of solid matter lying nearest these crystals 

 are flooded with water." 



5. The pieces regenerating in the highly dilute solutions 

 often show changes which indicate the great turgidity of 

 the tissues, in consequence of the abnormally great absorp- 

 tion of water. Before the polyp is formed, globular excres- 

 cences appear at the cut ends, and the new polyps are thicker 

 and much more nearly globular than the normal polyps. 

 The opposite phenomena are noted in the strongly concen- 

 trated salt solutions, in which polyps remain exceedingly 

 small. 



('). In conclusion I wish to give a few figures on the rela- 

 tion between regeneration and the absorption of water. Tn 

 order not to repeat what has already been said, I shall take the 

 figures from experiments in which the concentration of 

 the sea-water was increased by the addition of sodium 

 chloride, or decreased by the addition of fresh water (ti<-rino 

 water). According to F<rrh hammer, the amount of salt 



1 Hopri.-SiiYLER, rhytiioloyische Chentic (Berlin, 1877), p. 30. 



