PMAR OS 
a: 
ee See ee A ee 
I 884. ] Lvilvgy. 82 
almost entirely upon insects; sticklebacks eat about as much 
vegetable as animal substance; the small-mouthed atherinid La- 
bidesthes sicculus is a purely animal feeder, dividing itself almost 
equally between insects and entomostracans; Fundulus and Zygo- 
nectes take but little vegetable food ; the Cyprinidz, with a long 
intestine and pharyngeal teeth with a broad grinding surface, feed 
principally upon vegetable food, ingesting much mud therewith ; 
and in the Cyprinide, with hooked pharyngeal teeth and a short 
intestine, three-fourths of the food is animal. The smallest ento- 
mostracans form the first food of the young whitefish. 
Exact observations of this nature are scarce, and of great value, 
and Mr. Forbes has begun a needed work. 
SYMBIOSIS INTHE ANIMAL Kincpom.—Professor Hertwig, accord- 
ing to Nature, at the last meeting of German naturalists, read a pa- 
per on this subject. This term, symbiosis, first suggested by De 
Bary in connection with certain phenomena of the vegetable 
world, is here extended to the whole organic system. As distin- 
guished from ordinary parasitism, it is explained to mean the 
normal fellowship or association of dissimilar organisms which 
dwell together in a common abode for their mutual welfare. In ` 
the case of parasites the connection is altogether one-sided, one 
of the two organisms attaching itself to the other, and flourishing 
at its expense, as, for instance, the mistletoe on the apple tree. 
But in this newly-revealed phenomenon of symbiosis, which ap- 
pears to pervade the whole biological world, both associates are 
mutually beneficial, and in some instances even indispensable to 
each other. They act, so to say, like two partners in a well-reg- 
ulated business concern, codperating in the work of life, taking 
part in all its toils and troubles, and honorably sharing the com- 
mon profits. An illustration is drawn from the familiar hermit 
crab, one species of which, after taking possession of the first 
available empty shell, goes into partnership with a sea anemone 
( Adamsia palliata). This lonely creature, bright orange spotted 
with red, attaches itself to the roof of the common abode in such 
a position that its mouth and prehensile apparatus are always 
turned toward the head of its associate. It is thus enabled to 
join in all the expeditions of the restless hermit crab, and conve- 
niently share in the common plunder. In return for this service, 
the anemone protects his companion from his many enemies by 
means of the numerous long threads which it shoots out at the 
least alarm, and which are provided with millions of capsules 
charged with a stinging acid like that of the common nettle. So 
‘lose is the compact entered into by the two partners, that both 
have become indispensable to each other, as appears from a series 
of experiments made at the Neapolitan Aquarium. If the crab 
removed from his house, and this be stopped up so as to pre- 
vent his reéntering it, he will cast about for another shell, and 
