222 Miscellaneous. 



distinguished by a large gular sac (as in Velasia) and by the different 

 form of the caudal fin. The fish inhabits the brooks of some parts 

 of Chili, and is thrown away by the fishermen, who regard it as 

 unwholesome. — Wiegmann's Archiv, 1864, p. 107. 



On the Parasitic Nature of the Mistletoe. 

 By Joseph Boehm. 

 The author divides plants in general into the two following groups : — 



1. Chlorophyll-bearing, which assimilate the inorganic substances 

 drawn up by the roots from the soil, and thus become the ancestors 

 of all the rest of living nature. 



2. Chlorophyll-free, which either extract the assimilated juices 

 from other organisms, or nourish themselves from dead organic 

 matter. The latter plants alone, which Uve in the manner of ani- 

 mals, are regarded by the author as parasites. 



The Mistletoe has always been regarded as a plant which extracts 

 the organic juices from the plant on which it grows, and consequently 

 leads a parasitic existence. Boehm calls attention to the following 

 circumstances, which are particularly adverse to this view : — 



1 . The mode of insertion of the roots of the Mistletoe into the 

 wood of the tree on which it grows. 



2. The occurrence of the plant in question upon more than thirty 

 species of trees, all, however, of indefinite growth {Endumsprosser). 



3. The different results of the analysis of the ashes of the Mis- 

 tletoe and its supposed nutritive plants. 



4. The comparative size of the branches bearing Mistletoe above 

 and below the insertion of the apparent parasite. 



Recent investigations, repeated by Boehm, have placed it beyond 

 a doubt that, in trees with indefinite growth, the ascent of the crude 

 nutritive material takes place in the wood, but the assimilated forma- 

 tive juices descend in the bark. Even Knight was aware that when 

 annular strips are removed from the branches of these plants, the 

 latter become thickened only above the annular wound. 



This circumstance enabled the author to decide with absolute cer- 

 tainty that the Mistletoe has precisely the same relation to its nutri- 

 tive plant as a twig to its parent branch, or the graft to the stock. 

 From thirty branches bearing Mistletoe (on Acer, Populus, and 

 Quercus) the terminal twigs above the attachment of the Mistletoe 

 were cut away and the branches ringed below the Mistletoe. Whilst 

 in Acer and Quercus the branches thus treated usually died soon, 

 the Mistletoe plants on the Poplars not only continued their normal 

 growth, but a thickening of the branch above the annular wound 

 took place. This can only have occurred at the expense of the 

 juices assimilated by the Mistletoe. 



The fact that the development of the branches above the insertion 

 of the Mistletoe is hindered has, in the author's opinion, nothing to 

 do with the parasitic nature of that plant. The Mistletoe acts only 

 in the same way as any branch of the tree of which the development 

 is in advance of its neighbours. The injurious effect of the presence 



