DEC. 19, 1921 cobb: marionella 507 



Doubly refractive granules (MarionelUn) in the intestinal cells. — In the 

 single layer of cells composing the intestine, an undescribed species of Mari- 

 onella presented about twenty scattered special cells, more numerous and 

 closer together anteriorly, each packed with doubly refractive granules 

 (marionellin) mostly of very small size. Marionellin occurs in other species 

 of Marionella. 



These special intestinal cells were not distributed along a definite longi- 

 tudinal line as in Ironus, where there is a decided dorso-ventral symmetry 

 to the intestine due to the dorsal cells having a different character from 

 the ventral. The interspaces between these special cells in this species of 

 Marionella increased rather regularly from front to rear. 



The discovery of these special intestinal cells is an additional observation 

 indicating diferentiation among the cells of the nema intestine. Such differ- 

 entiated cells are now known to the writer in the following genera, among 

 others: Enoplus, Bathylaimus, Ironus, Mononchus, Eurystoma (all carniv- 

 orous). It seems very reasonable to suppose that these differentiated cells 

 may have functions similar to those of the glands accessory to the intestine 

 of other and larger animals. Assuming that digestion in nemas has a general 

 similarity to that of the higher animals, it would seem that gastric, hepatic, 

 renal and other functions must exist in some form in the nema; thus far, 

 however, very few of these functions can be assigned to special organs, as 

 few or no such special organs exist. Instead of each cell of the intestine 

 carrying out all of these distinct functions, in view of the above observations 

 there is now morphological evidence of "division of labor," and when these 

 differentiated cells have been adequately investigated, we shall probably be able 

 to assign to them definite functions, and, for illustration, be able to apply to 

 them some such terms as "hepatic cells," "renal cells," "spleenic cells," etc. 



Tail. — The tail in Marionella takes on one of two distinct forms, accord- 

 ing as there is or is not a spinneret present. If there is no spinneret the tail 

 is conoid from the anus to the acute terminus, sometimes however tapering 

 a little more rapidly in the anterior portion than elsewhere. In species 

 possessing this form of tail, usually the tail of the male is the shorter, and 

 the narrow conoid posterior part may appear rather as an appendage to the 

 short but bulky anterior part. Most of the species, however, possess three 

 well-developed unicellular caudal glands and a blunt, conoid, unarmed, and 

 symmetrical terminal spinneret about one-fourth as wide as the base of the 

 tail. If any setae occur on the tail, they are exceedingly small and very 

 inconspicuous. The three quite separate ducts of the caudal glands are 

 plainly visible in the tail and end posteriorly in three separate ampullae. 

 The unicellular glands themselves are arranged in a loose tandem in front 

 of the anus, the foremost being removed a distance from the anus several 

 times as great as the corresponding body diameter. 



Lateral fields: glandtdar cells. — The lateral fields are usually about half 

 as wide as the body, and contain large, granular, ellipsoidal, glandular cells 

 about one-third as wide as the body and emptying on the surface of the 

 cuticle by means of exceedingly minute pores. These large glandular cells 

 are situated from point to point throughout the length of the body, the 

 distance between them being from one to four times as great as the width 

 of the body 



Renette. — The renettei^cell is invariably situated behind the neck and 

 empties by means of a long, narrow, faintly visible duct. The narrow in- 



