"^OL. 3] Bovard. — Condylostoma patens. 345 



groove, and is 2iiore accurate than Stein's, for it was made from 

 a quiescent individual and not from one flattened nnder the 

 cover glass. Biitschli ('89) has followed Stein, so his figures 

 continue the same erroneous presentation of the form. 



The variation of the figures is easily explained, for I have 

 found that the amount of food present and the density of the 

 water have much to do with the shape of the animal. Those that 

 are well extended and full of vacuoles lose to a considerable ex- 

 tent the tapering form of the body and become "beutelformig" 

 (Biitschli) or "walzenformig" (Stein). Well-fed individuals 

 prior to division become greatly elongated, and as the food va- 

 cuoles fill out the posterior tip, the body may become "beutel- 

 formig" and look a great deal like Stein's figures except in the 

 matter of the size of the buccal groove. Animals that are not 

 full of vacuoles but are otherwise in a normal condition show 

 invariably the tapering of the body toward the posterior end and 

 the strongly curved posterior tip. 



ECTOPLASMIC STRUCTURES. 



Pellicula. — The entire animal is covered M'ith a thin trans- 

 parent homogeneous membrane. This is very elastic and allows 

 of the freest movement, but still preserves the external form. 

 It is thinnest over the middle i^arts of the body and thickens 

 considerably toward the posterior end. Maupas ('83) calculates 

 that the thickness varies from 2 to 4/*, while Biitschli ('89) be- 

 lieves that it may reach 8|U.. By some it is claimed that this layer 

 shows transverse striation and markings of various kinds. In 

 Condylostoma there is no regular pattern and the modifications 

 of the pellicula proper are exceedingly variable and not always 

 visible. In the living animal this membrane is very transparent 

 and recognized only when the animal bends sharply, making a 

 fold in its side. In sections the pellicula appears as a thin non- 

 staining homogeneous layer outside of all the other structures. 



Surface Markings. — The surface of the body is marked by 

 primary ridges which run the entire length of the animal. These 

 mark the position of the myonemes. The space between the 

 primary ridges is divided into many small polygonal areas 



