SPECIAL ME THOD S. 22 3 



true protein crystalloids occur in many marine algae. These 

 must not be confused with the so-called rhodospermin-crys- 

 talloids which are formed after the algae have been killed in 

 a solution of common salt or in spirit. 



395. Rhodospermin consists chiefly of hexagonal prisms or 

 plates which are colored deep red (Fig. 52). They are 

 insoluble in water, alcohol, glycerine, sulphuric, nitric, hydro- 

 chloric, and acetic acids, and in alkalies. They become 

 gradually destroyed and invisible on boiling in sulphuric 

 acid, hydrochloric acid, or potash. Iodine colors them at 

 first golden yellow and later deep brown-yellow. They 

 are not colored by concen- 

 trated nitric acid, but on 



the subsequent addition 

 of ammonia become most 

 clearly yellow. Rhodo- 

 spermin often swells mark- 

 edly in a potash Solution, FlG . 52 ._ Rho dospermin crystals from Cera- 

 bur rnnfrarf-*; acrain tn i>c mimr*trm. a, formed in the cortical tis- 



ItS SU e ; &, rhodospermin formed free in the fluid. 



original bulk on the addi- After J " Klein ' 



tion of acids, while, at the same time, the color which has 



disappeared in the potash reappears (cf. J. Klein I, 55). 



Whether we are justified by these reactions in including 

 rhodospermin among the proteids, as is commonly done, 

 seems to me at least doubtful. B.ut, at any rate, the rhodo- 

 spermin crystalloids do not belong in the same category 

 with other crystalloids, for they represent, as has already 

 been remarked, an artificial product arising through the 

 action of reagents. 



iz. Rhabdoids (Plastoids). 



396. Gardiner observed (I) in most of the epidermal cells 

 of Drosera dichotoma, as well as in those of Dioncea, spindle- 

 shaped or needle-shaped bodies which he first termed plas- 

 toids and later, rhabdoids.* These usually occur singly in 

 the cells, which they cross diagonally. They are fixed by 



* From % pdfidoS, the rod. 



