INTRODUCTION TO CRYPTOGAMTC BOTANY. J 73 



Slightly, and I may add truly, as these are often indicated in 

 KUtzing's exquisite plates, they are often still more obscurely 

 marked under the microscope. The endochromes of neigh- 

 bouring cells often communicate by more or less delicate 

 threads,* by which, probably, the same purpose is answered 

 as by the canals so frequent in the cells of Phsenogarns. 

 Sometimes the processes of the endochromes seem to terminate 

 in real canals, answering to those of a neighbouring cell. 

 There are, besides, frequently large intercellular sjjaces, and 

 the walls of the cells, when well developed, often show dis- 

 tinct strata. The cells, moreover, pass abruptly from sacs 

 into threads, or the contrary, exhibiting great variety of form 

 in the same part of a plant, and in the same plane or section, 

 and it often happens that towards the circumference the walls 

 are so intimately combined, that a thin slice merely shows a 

 firm transparent mass, perforated with cavities, and this even 

 in cases where the component threads or cells are mostly free, 

 as, for instance, in Furcellaria fastigiata. The cells them- 

 selves, as also the spores, often contain distinct free granules, 

 which (Fig. 46, d), in the former case, at least, appear to be 

 amylaceous. 



149. Rhodosperms, though their genera have often definite 

 geographical limits, do not differ greatly as a whole, in this 

 respect, from the other divisions of Algse. They are found in 

 every sea, and while Iridcea radula, Bory, accompanies Ade- 

 nocystis Lessonia, and a magnificent Scytothalia, in Cock- 

 burn Island, beyond the 60° of south latitude, the Chloro- 

 sperms being represented on the shore by Ulva crispa and 

 an Oscillatoria, there are representatives of the three great 

 divisions in the northern hemisphere, at -least as high as 73°. 

 Laminaria Saccharina has been found as high as 74.40, 

 and an Oscillatoria in 75.49, and, probably, even there, Rhodo- 

 sperms have not entirely ceased. Though, however, they form 

 vast masses in many latitudes, these cannot be compared with 



* An example of communicating enJochromes is figured at Fig. 44, d, 

 from the tissue which surrounds the conceptacles of Gigartina pistillata, 

 the divisions of the several cells being invisible under the microscope. 



