134 PROTOPLASM 



spends a bundle of fibrillse in the underlying cell, which 

 can similarly be well observed in the living condition. 



In the investigation of the living Hydatina I also ob- 

 served the meshed structure very plainly in the protoplasm 

 of other cells, of which I will give a brief account. It 

 showed up most plainly in the cells of the so - called 

 gizzard, accompanied by the appearance of very pronounced 

 nodal points in the framework, an appearance, however, 

 which is partly called forth by granules deposited in it. On 

 the surface of each cell the radiate layer of marginal alveoli 

 was very distinct. In the cells of the gastric glands a 

 marginal alveolar layer could also be made out. The pro- 

 toplasm of these cells was either merely a reticular mesh- 

 work, or else a meshwork arranged in striae. In the latter 

 case the striation was directed towards the spot at which 

 the gland opened into the mid gut. Especially in the neigh- 

 bourhood of this spot the reticular structure could always be 

 observed very plainly, which partly depends on the fact that 

 numerous granules are lodged in the nodal points. We are 

 dealing here, no doubt, with the secretion products of the 

 gland, which are collected abundantly in the framework of 

 the protoplasm in this region. 



The meshwork structure frequently appeared especially 

 distinct in the two peculiar strands which ascend for- 

 wards and obliquely outwards from the end gut. Whether 

 these strands are glandular, or are a kind of suspensory liga- 

 ment for this portion of the gut, I will not venture to 

 decide. Finally, the cells of the foot gland show in many 

 places the reticular structure fairly well, though not so 

 clearly as the last-mentioned histological elements. 



Very thin transverse or longitudinal sections through the 

 body wall of Luiribricus tcrrcstris show very beautifully the 

 longitudinally striated structure of the epithelial cells which 

 are not modified into gland cells (i.e. indifferent or support- 

 ing cells Plate VI. Fig. 3). I will not go more specially 

 into the way in which the glandular and supporting cells 

 are arranged with regard to one another, since that has 

 already been recently described in detail elsewhere. Fine 

 longitudinal sections through the supporting cells (see the 



