372 ALFRED GIBBS BOURNE. 



from the endoplasm ; and in the second place, that the 

 " endoplasm " is composed of a number of cells. Both these 

 are very startling views, and while I feel sure that the conclu- 

 sions are erroneous, I have observed certain phenomena which 

 may have given rise to them. 



Gulliver writes, " In the process of hardening this layer 

 (the exoplasm) readily separates from the subjacent softer 

 endoplasm." I have noticed in hardening specimens in a 

 watch-glass for section-cutting, and also under the cover-glass 

 for subsequent staining and mounting as whole preparations, 

 that the peripheral portion which is first attacked by the 

 hardening reagent often becomes separated from the still 

 living and shrinking central mass, another layer is then 

 attacked, and so the whole structure may harden in irregular 

 layers. The hardened portions break away with extreme 

 readiness from the unhardened ones. 



Very curious appearances are sometimes thus produced, but 

 I am convinced that the phenomenon is a mere accident in 

 the hardening process. The examination of living specimens 

 can leave no doubt as to the absence of any permanent differ- 

 entiation of the body substance into exoplasm and endoplasm. 

 With regard to the structures which Gulliver takes to be cells 

 building up the '^ endoplasm," and which Lankester has sug- 

 gested may be swarm-spores, I have formed a less definite 

 opinion. In a living specimen one can see no such structure, 

 but in hardened specimens one does undoubtedly find small 

 rounded portions of the protoplasm lying in and yet separated 

 from the rest of the protoplasm. These bodies have, however, 

 no definite and constant characters, they differ considerably 

 in size, sometimes include one nucleus, sometimes more than 

 one, and frequently none at all. It is difficult to detail the 

 precise appearances which lead me to the conclusion ; but I 

 am much inclined to think that we have here merely an acci- 

 dental rounding off of portions of the protoplasm, which takes 

 place during the hardening process. I have seen similar 

 phenomena in specimens which have died from having been 

 kept mounted for a long time under a cover-glass. The body 



