26 THE GENERAL CHARACTERS OF CELLS, BY S. STRICKER. 



entirely from that of contractile protoplasm. But the mus- 

 cular fibres are collected into great masses, permitting macro- 

 scopic investigations of a chemical and physical nature to be 

 undertaken upon them which are not applicable to microscopic 

 inquiries. The range and variety of experiments performed 

 under the microscope is undoubtedly constantly enlarging, and 

 consequently improved means will be hereafter obtained for 

 acquiring a knowledge of the physiology of cells. At present, 

 however, this must still rest on the physiology of muscle, as 

 probably it will continue in great measure to do, even when it 

 has received its greatest development. With regard to the 

 specific functions of cells, we must limit ourselves to the general 

 statement that there are cells possessing very various physiolo- 

 gical functions, as nerve cells, muscle cells, gland cells, etc. ; 

 and, inasmuch as we are unable to conceive any functional 

 process to take place in a cell without the occurrence of chemi- 

 cal processes, we must suppose that the specific functions of 

 the cells in these several cases are essentially dependent on the 

 nature of the chemical processes occurring in them. In the 

 case of the muscles and in that of nerve cells, chemical investi- 

 gations furnish us with no information beyond that of the dead 

 tissue ; whilst, in respect to gland cells, we do obtain some 

 little insight into the nature of the chemical processes through 

 an investigation of the secretion. Thus we know that there 

 are cells which produce fat (mammary and sebaceous glands), 

 others which develop pepsine, and further, that as a conse- 

 quence of the activity of muscle and nerve tissue, acids are 

 formed* 



From the results of the chemical investigation of protoplasm 

 it would appear that, in all probability, it contains a consider- 

 able proportion of myosine (Kuhne).f In some protoplasmic 

 masses, protagon (Hoppe-Seyler, Fischer), in others glycogen, 

 has been shown to be present, and in some few vegetable cells 

 cholesterinef has been found. 



It may be questioned, and remains to be shown, whether the 



* Du Bois, Funke. 



t See Kiihne, Lehrbuch der Physiologische Chemie. 



J Hoppe-Seyler, Med. Chem. Untersuchungen. 



