apkil, loo:.] LOEW & ASO.—ON PHYSIOL. BALANCED SOLUTIONS. 73 



accumulation in the chloroplast impossible, all carbhydate pro- 

 duced by assimilation of carbon being at once transformed into 

 protein required for the rapid growth; on the other hand a 

 surplus of potassa led to a considerable accumulation of starch, 

 when nitrogen was present in a minimum amount, while an 

 undue simultaneous maximum of nitrogen and potassa led to 

 the accumulation of much protein 1 } in vacuole and cytoplasm, 

 and but little starch becomes visible. 



Under certain conditions the chloroplast grows more rapidly 

 than the cytoplasm, finally filling this out entirely and render- 

 ing the nucleus invisible ; under other conditions again the 

 cytoplasm grows more than the chloroplast, the latter chang- 

 ing its spiral form finally to a straight line. 2) 



Again in certain culture solutions the cytoplasm is rendered 

 turbid from fine precipitates of phosphates, in others again the 

 filaments break up into single cells, which remain perfectly 

 healthy. The phenomenon is in many cases due to increased 

 turgor/ 



Some of the many trials 4) may here be mentioned. As favor- 

 able culture solutions served the following: 



D This protein is of very labil nature. Cf. O. Loew and Th. Bokorny in „ Die 

 chernische Energie der lebenden Zellen " by O. Loew. 



2 ) During such observations, attention must be paid to the presence of Chritridia, 

 parasites which easily perforate the cell-walls of Spirogyra. Brown has observed over 

 20 species attacking various algse. Sometimes Spirogyra is attacked also by Pseudospora, 

 which is a mixomycet according to Zopf. These parasites may often be destroyed by 

 placing the algte for 1-2 days in a 1 per mille solution of phenol in wellwater, 

 Parasites will doubths; become most abundant after a portion of the Spirogyra cells 

 present had died, furnishing by exosmose from the vacuole organic nutrients for the 

 parasites outside and attracting them to the filaments. The presence of infusoria is 

 favorable as they (especially Vorticella) devour Ckytridia. 



3 ) This phenomenon was also observed when Spirogyra was kept in very moist 

 air, i.e. under a bell-jar spread on moss, thoroly moistened. Once it was observed by 

 us also by touching the filaments with very dilute Os0 4 . W. Benecke made especial 

 studies on this subject. J. w- Bot. 1898. 



4 > Spirogyra is very sensitive to ammonium salts, especially in weak alkaline 

 culture solutions, while nitrates may serve well as source of nitrogen even at concen- 

 trations of 0.2^. Monoammoniumphosphate which is of acid reaction, may at a 

 concentration not higher than 0.05^ serve, however, as a source of nitrogen in weak- 

 acid culture solutions. 



