II. A FLORA WITHIN ANIMALS. 35 



greatest degree of perfection, attaining dimensions of one line in length by the 

 of an inch in breadth, with remarkably distinct articuli (PL V. 14, 15). 



Within the ventriculus of Passalus cornutus, filaments of the plant often acquire 

 a length of i of a line, and occasionally even of a J line, with a diameter of the 

 irJo o of an inch. 



The articuli of Arthromitus, excepting when they contain spores, are usually 

 indistinct, arising apparently from the general amorphous character of the contents 

 which have the same or very nearly the same refrangibility as the cell-wall. 

 Their average dimensions are the T7 tb^ f an inch m length by the T ^^- of an 

 inch in breadth. In the variety which grows within the large intestine of Julus 

 marginatus, the articuli are about the length of the diameter of the filaments, or a 

 very little longer. In that of Passalus cornutus, they average the y^^tf of an 

 inch in length. 



The filaments of Arthromitus are cylindrical, and only depart from this general 

 form in the very slight dilatation which often exists in the articuli, giving them a 

 keg-shaped appearance. The contents of the thallus are always amorphous and 

 hyaline, never having even the faintest appearance of granules. 



Not unfrequently, in the largest variety of Arthromitus, several articuli along 

 the course of the thallus are contracted into a solid columnar form, not more than 

 half the diameter of the others (14, c). 



1. Of the /Spores of Arthromitus. These are always observed single within the 

 articuli. Most frequently, they exist only in the articuli which form the distal 

 portion of the thallus, but they are also often seen in any part of the length of the 

 latter, sometimes at intervals of a variable number of articuli containing none; 

 and occasionally, they exist in all the articuli. 



In the largest variety of Arthromitus, in which the character of the sporuli is 

 best observed, the articulations which contain them are slightly contracted, or have 

 a little less diameter than the others (15, b). 



The position of the sporuli is usually oblique, and they alternate in this direction 

 in the different articuli ; frequently, they are arranged longitudinally, never trans- 

 versely. They are elliptical in form, transparent, highly refracting like oil-glob- 

 ules, of a light amber-color, and are amorphous in structure. On the average, they 

 measure the i^inr f an ^ nc ^ * n length, by the 3-20^7 of an inch in breadth. In 

 the Arthromitus of Passalus cornutus, they measure the jTTo'oTr f an inch in length, 

 by the ^-J^Tr f an ^ ncn i Q breadth. In the largest variety of the plant, they 

 measure the y-gVj- of an inch in length, by the y^o^ of an inch in breadth. 



2. Of the Development of the Spores. This is most readily observed within the 

 articuli of the largest variety of Arthromitus growing within the large intestine of 

 Julus marginatus (14, 15). The sporuli appear to originate in a gradual contraction, 

 condensation, and consolidation of the protoplasmoid contents of the articulations. 

 Within these, may frequently be observed single oval or clavate, or bent oval or 

 reniform masses, faintly outlined, and nearly filling their cavity (15, a). The masses 

 gradually contract to the bulk of the spores, and become distinct, shining, and 

 highly refracting, and in this condition constitute the fully-developed sporuli (6). 



