26 A FLOEA WITHIN ANIMALS. II. 



primordial utricle within the permanent cell-wall, is deeper than in the former 



cases. 



Next succeeds a distinct separation of the material which is to constitute the 

 contents of the new secondary cell from that of the principal cell, and a thin trans- 

 parent partition is formed, between the two portions, continuous at its outer margin 

 with the enveloping primordial utricle (23, c). 



It is not until this period that examples of the plant are found in which there 

 exists an evident constriction in the permanent cell-wall corresponding to the 

 margin of the partition separating the secondary from the principal cell. This 

 constriction deepens, and continues to advance concentrically until it completely 

 divides the thin transparent partition formed from the primordial utrical and sepa- 

 rating the two distinct masses of cell-contents (19), and thus we have formed from 

 the principal cell a perfect new or secondary cell. In the case of Enterohryus 

 elegans, upon which the above observations were made, the distal extremity of the 

 principal cell, after the complete development of secondary cells still remaining in 

 connection with the former, is obtusely rounded, a little broader than the second- 

 ary cells, and appears to indicate that these continue their attachment some time 

 after they are fully formed. 



From the truncated appearance of the principal cell being observed so frequently 

 in Enterohryus attenuatus, I suspect that the secondary cells, after their production, 

 detach themselves very rapidly, giving rise to the watch-crystal-like appearance of 

 the free end of the cell, from the thinness of the new membrane continuous at 

 its circumference with the older, thicker, and stronger permanent cell-wall (PL 

 III. 17). 



In Enterohryus elegans and Enterohryus spiralis, the production of one secondary 

 cell is rapidly followed, or even accompanied by another, developed from the prin- 

 cipal cell. In rare cases, even a third cell commences its development from the 

 principal cell before the detachment of the terminal cell. 



3. Of the Pedicle and Mode of Attachment. (PI. II. 4,c; III. 6, 9, 11, h.) The 

 pedicle of attachment of Eiderohryus is more or less cylindrical, solid, hard, trans- 

 parent, amorphous in structure, yellowish or brownish in color, and faintly striated 

 longitudinally. Its length varies with the age of the plant, and, to some extent, 

 with the position of attachment. 



In the youngest plants it looks like a very slight conical or mound-like elevation 

 or thickening of the basement-membrane of the mucous membrane from which the 

 plant grows (PL II. 3, h). It is colorless, and, in these cases, from its amorphous 

 appearance, appears to be part of the structure of the basement-membrane. 



As the principal cell grows in length the pedicle does so also, and, in a little 

 time, appears quite a distinct structure from the basement-membrane to which it is 

 attached. It reaches its greatest degree of development in Enterohryus elegans, and 

 when the latter is attached to the exterior of entozoa, it becomes much longer than 

 in the plants growing from the mucous membrane of the intestine in which the 

 entozoa are found (PL VI. 6, e; 7, d). Upon an Ascaris infecta, I have observed indi- 

 viduals of Enterohryus with the pedicle the ^ ^ro of an inch in length, while, in those 



