1 6 The Mycetozoa, and 



consider briefly what is meant by the expression naked 

 protoplasm. 



When in the seventeenth century the microscope was 

 applied to vegetable tissues, especially by our countrymen 

 Hooke and Grew, and by the Italian Malphigi, they were 

 struck with the presence of small walled cavities in the fleshy 

 parts of plants. These Hooke called cells, and Grew and 

 Malphigi utricles or bladders. Hooke' s name has stuck to 

 them, and plays a great part in botanical writings from 

 his day to the present. We are accustomed to regard the 

 cell division as the determining factor in growth, the mode 

 of division providing, as it were, the form which the plant 

 is to assume : and especially since the days of Schleiden 

 and Schwann when the cell came to be regarded as the 

 structural unit in the growth of plants the tracing of 

 cell development, and the structure of the parts of the cell 

 (especially the cell walls), and the behaviour of the cell, have 

 been studied with the utmost care. Presently it came to be 

 seen that the cell walls were inert and by no means the most 

 important part of the structure, but that the slimy contents 

 of the little box, which had been treated with scant atten- 

 tion in the earlier stages of study, were, after all, the most 

 remarkable part of the cell, and were to all appearance the 

 basis of both animal and vegetable life. When attention 

 was first called definitely to it in the vegetable kingdom it 

 was termed protoplasm, by Mohl ; when first accurately 

 observed in animals it was named sarcode by Dujardin ; 

 and by-and-by it was found that protoplasm and sarcode 

 were one and the same thing. Then instances were 



