ENCYSTMENT OF TARDIGRADA. 841 



the opaque outer case, and it is hoped that he will soon observe the sequence of the 

 changes. 



Seen within the inner case (fig. 4), the contained animal shows a faint segmentation, 

 three transverse furrows dividing it into four nearly equal parts. When the animal is 

 squeezed out no segmentation can be noticed (fig. 5). It is covered by a very thin 

 cuticle and has a somewhat undulate outline. 



Even in this latest stage, the animal has not lost every trace of its former self. The 

 eye-spots persist as long as an animal has been watched, and the fat cells in the blood 

 continue recognisable. There are also some cells, with dark contents, in the centre of 

 the body, which I take to represent the stomach. The eye-spots become very large and 

 diffuse, of loosely agglomerated granules (fig. 5). 



Animals squeezed from the cyst at an early stage showed, as above remarked, no 

 trace of limbs. At a later period, but at an unknown interval of time from the 

 formation of the cyst, a squeezed-out animal had obtuse papillae for limbs, without 

 trace of claws (as shown in fig. 14). There was at this stage a very thin cuticle, and 

 underneath it a lax cellular tissue of large obscurely polygonal cells. The supposed 

 cells of the stomach, with brown contents, were still conspicuous ; the fat cells were 

 few ; there was no trace of pharynx or teeth. 



I have no observations between this stage and the final emergence, shown in fig. 12. 



This was witnessed on several occasions, and is sufficiently curious. The animals 

 were remarkably large and lusty, considering the enormous expenditure of material in 

 making the various cases and integuments, and the small cyst from which they issued. 

 They were fully provided with all the organs they possessed when entering the cyst ; 

 well -grown claws, pharynx, teeth, etc. 



The case splits at the posterior constriction before alluded to, and the end portion 

 opens like a hinged lid, permitting the animal to walk out backward. The emergence 

 occupied several hours, and after a severe struggle and the extrication of one pair of 

 limbs, the animal would take a long rest before recommencing the struggle. Fully 

 emerged, the creature did not appear greatly smaller or conspicuously different from 

 what it was originally. 



The process of encystment, as observed in M. dispar, and described above, differs 

 in many respects from that sketched by Professor Lauterborn, yet there are many 

 points of correspondence. M. macronyx and M. dispar are the only two species yet 

 observed which secrete a special outer case. Those two species are of aquatic habit, 

 while all others of which I have seen cysts are normally moss-dwellers. 



Cysts of Other Species. 



Cysts of a good many species of Tardigrada have been seen, but I have had no 

 opportunity to study any of them except M. dispar. 



All the cysts which I have seen are a good deal alike, and none of them, except 



