CHANGES OF FORM IN CELLS. 25 



As we now know from the researches of Schweigger-Seidel 

 and La Valette, that the spermatozoids are not essentially 

 nuclear structures, but are also composed of protoplasm, their 

 movements must likewise be attributed to this substance. 



Cell division and germination are likewise consequences of 

 its contractility. 



Lastly, also the migrations of cells are dependent upon it, of 

 the importance of which to the organism at large we have 

 already spoken. 



Hermann has made an attempt to explain the phenomena of move- 

 ment. The protrusion of a process, he says, can only be regarded in 

 the light of a partial contraction, which, whilst it occurs in the direc- 

 tion of a striving on the part of the cell (or, better, of a striving sur- 

 face), drives the superjacent segment before it. If, then, renewed 

 contraction continually occur, it must always become thinner and 

 more thread-like. Hermann makes no remark, however, on the re- 

 traction of the processes. But if Hermann's theory were adopted, 

 there would not be much difficulty in explaining this by admitting 

 contractions in other directions. 



METAMORPHOSIS OF TISSUE. Only a single direct observa- 

 tion by Kuhne* exists in regard to the metamorphosis of tissue 

 that takes place in the living cell. According to his researches, 

 ciliary movement is connected with the consumption of oxygen, 

 and there can be no doubt that the cells are capable of with- 

 drawing oxygen from loose chemical combination. Ciliary 

 movement continues in an atmosphere of hydrogen, and in a 

 solution of oxygenated hoemoglobin, till all the loosely com- 

 bined oxygen of the latter, as may be proved by spectrum ana- 

 lysis, is consumed. Moreover, from indirect experiments, we 

 are justified in admitting a metamorphosis of tissue in the cells, 

 and are hence in a position to realize the more accurate data 

 which have been acquired respecting the metamorphosis of 

 tissue in animals. The results which have been arrived at from 

 investigation on muscles are particularly important. Muscular 

 fibres are metamorphosed cells, and they consist essentially of 

 contractile substances, the internal structure of which differs 



* Max Schultze's Archiv, Band ii. 



