212 



BOTANICAL MlCROl^ECHNIQUE. 



6. The Iridescent Plates of various Marine Algae. 



371. As was first described in detail by Berthold (II, 685)^ 

 there occur in the superficial cells of some marine algae char- 

 acteristic iridescent protoplasmic plates, which are very prob- 

 ably to be considered as organs for protection from too- 

 strong illumination. In the Chylocladicz they consist of a 

 strongly refractive mass in which small granules of somewhat 

 varying size are imbedded (cf. Fig. 47, a, p\ In profile view 

 they show a striation parallel to the 



surface of the plates and suggest- 

 ing their composition of separate 

 lamellae (cf. Fig. 47, b\ These 

 plates are always very sharply dif- 

 ferentiated from the cytoplasm. 



In distilled water vacuoles occur 

 in them, most probably in conse- 

 quence of the swelling of the glob- 

 ules imbedded in its mass; and 

 finally, the plates show a completely 



s P n ^ structure - 



372. For/*^ the protoplasmic 

 p l a tes Berthold recommends chiefly 

 a concentrated solution of iodine in sea-water (cf. 301) or 

 osmic acid ( 308). Neither of these, however, completely 

 preserves the structure. 



Whether these bodies are to be included with elaioplasts,. 

 as has lately been held to be probable by Wakker (I, 488), 

 must be determined by further researches. 



7. Microsomes and Granula. 



373- Under the term microsomes are usually included all 

 those small and mostly globular bodies which are distin- 

 guishable by their different refractive power from the main 

 mass of the cytoplasm. But it can no longer be doubted 

 that these include bodies of very different composition, and 

 it is not possible to speak of special reactions of the micro- 

 somes. 



res (x 250). After Berthoid. 



